[Federal Register Volume 88, Number 234 (Thursday, December 7, 2023)]
[Notices]
[Pages 85244-85265]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-26913]


-----------------------------------------------------------------------

DEPARTMENT OF COMMERCE

National Oceanic and Atmospheric Administration

[RTID 0648-XD253]


Takes of Marine Mammals Incidental to Specified Activities; 
Taking Marine Mammals Incidental To U.S. Navy 2024 Ice Exercise 
Activities in the Arctic Ocean

AGENCY: National Marine Fisheries Service (NMFS), National Oceanic and 
Atmospheric Administration (NOAA), Commerce.

ACTION: Notice; proposed incidental harassment authorization; request 
for comments on proposed authorization and possible renewal.

-----------------------------------------------------------------------

SUMMARY: NMFS has received a request from the U.S. Navy (Navy) for 
authorization to take marine mammals incidental to 2024 Ice Exercise 
Activities in the Arctic Ocean. Pursuant to the Marine Mammal 
Protection Act (MMPA), NMFS is requesting comments on its proposal to 
issue an incidental harassment authorization (IHA) to incidentally take 
marine mammals during the specified activities. NMFS is also requesting 
comments on a possible one-time, 1-year renewal that could be issued 
under certain circumstances and if all requirements are met, as 
described in Request for Public Comments at the end of this notice. 
NMFS will consider public comments prior to making any final decision 
on the issuance of the requested MMPA authorization and agency 
responses will be summarized in the final notice of our decision. The 
Navy's activities are considered military readiness activities pursuant 
to the MMPA, as amended by the National Defense Authorization Act for 
Fiscal Year 2004 (2004 NDAA).

DATES: Comments and information must be received no later than January 
8, 2024.

ADDRESSES: Comments should be addressed to Jolie Harrison, Chief, 
Permits and Conservation Division, Office of Protected Resources (OPR), 
NMFS and should be submitted via email to <a href="/cdn-cgi/l/email-protection#105944403e5471667963507e7f71713e777f66"><span class="__cf_email__" data-cfemail="d59c8185fb91b4a3bca695bbbab4b4fbb2baa3">[email protected]</span></a>. 
Electronic copies of the application and supporting

[[Page 85245]]

documents, as well as a list of the references cited in this document, 
may be obtained online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities. In case of problems accessing these documents, 
please call the contact listed above.
    Instructions: NMFS is not responsible for comments sent by any 
other method, to any other address or individual, or received after the 
end of the comment period. Comments, including all attachments, must 
not exceed a 25-megabyte file size. All comments received are a part of 
the public record and will generally be posted online at https://www.fisheries.noaa.gov/permit/incidental-take-authorizations-under-marine-mammal-protection-act without change. All personal identifying 
information (e.g., name, address) voluntarily submitted by the 
commenter may be publicly accessible. Do not submit confidential 
business information or otherwise sensitive or protected information.

FOR FURTHER INFORMATION CONTACT: Leah Davis, OPR, NMFS, (301) 427-8401.

SUPPLEMENTARY INFORMATION: 

Background

    The MMPA prohibits the ``take'' of marine mammals, with certain 
exceptions. Sections 101(a)(5)(A) and (D) of the MMPA (16 U.S.C. 1361 
et seq.) direct the Secretary of Commerce (as delegated to NMFS) to 
allow, upon request, the incidental, but not intentional, taking of 
small numbers of marine mammals by U.S. citizens who engage in a 
specified activity (other than commercial fishing) within a specified 
geographical region if certain findings are made and either regulations 
are proposed or, if the taking is limited to harassment, a notice of a 
proposed IHA is provided to the public for review.
    Authorization for incidental takings shall be granted if NMFS finds 
that the taking will have a negligible impact on the species or 
stock(s) and will not have an unmitigable adverse impact on the 
availability of the species or stock(s) for taking for subsistence uses 
(where relevant). Further, NMFS must prescribe the permissible methods 
of taking and other ``means of effecting the least practicable adverse 
impact'' on the affected species or stocks and their habitat, paying 
particular attention to rookeries, mating grounds, and areas of similar 
significance, and on the availability of the species or stocks for 
taking for certain subsistence uses (referred to in shorthand as 
``mitigation''); and requirements pertaining to the mitigation, 
monitoring and reporting of the takings are set forth. The definitions 
of all applicable MMPA statutory terms cited above are included in the 
relevant sections below.
    The 2004 NDAA (Pub. L. 108-136) removed the ``small numbers'' and 
``specified geographical region'' limitations indicated above and 
amended the definition of ``harassment'' as applied to a ``military 
readiness activity.'' The activity for which incidental take of marine 
mammals is being requested addressed here qualifies as a military 
readiness activity.

National Environmental Policy Act

    To comply with the National Environmental Policy Act of 1969 (NEPA; 
42 U.S.C. 4321 et seq.) and NOAA Administrative Order (NAO) 216-6A, 
NMFS must review our proposed action (i.e., the issuance of an IHA) 
with respect to potential impacts on the human environment. 
Accordingly, NMFS plans to adopt the Navy's Environmental Assessment 
(EA), provided our independent evaluation of the document finds that it 
includes adequate information analyzing the effects on the human 
environment of issuing the IHA. The Navy's EA was made available for 
public comment at https://www.nepa.navy.mil/icex/ from September 29, 
2023 to October 13, 2023.
    We will review all comments submitted in response to this notice 
prior to concluding our NEPA process or making a final decision on the 
IHA request.

Summary of Request

    On May 24, 2023, NMFS received a request from the Navy for an IHA 
to take marine mammals incidental to submarine training and testing 
activities including establishment of a tracking range on an ice floe 
in the Arctic Ocean, north of Prudhoe Bay, Alaska. Following NMFS' 
review of the application, the Navy submitted a revised application on 
October 13, 2023 that removed the request for take of bearded seal and 
included an updated take estimate for ringed seals. The application was 
deemed adequate and complete on October 19, 2023. The Navy's request is 
for take of ringed seal by Level B harassment. Neither the Navy nor 
NMFS expect serious injury or mortality to result from this activity 
and, therefore, an IHA is appropriate.
    NMFS previously issued IHAs to the Navy for similar activities (83 
FR 6522; February 14, 2018, 85 FR 6518; February 5, 2020, 87 FR 7803; 
February 10, 2022). The Navy complied with all the requirements (e.g., 
mitigation, monitoring, and reporting) of the previous IHAs, and 
information regarding their monitoring results may be found in the 
Estimated Take section.

Description of Proposed Activity

Overview

    The Navy proposes to conduct submarine training and testing 
activities, which includes the establishment of a tracking range and 
temporary ice camp, and research in the Arctic Ocean for 6 weeks 
beginning in February 2024. Active acoustic transmissions may result in 
occurrence of Level B harassment, including temporary hearing 
impairment (temporary threshold shift (TTS)) and behavioral harassment, 
of ringed seals.

Dates and Duration

    The specified activities would occur over approximately a six-week 
period between February and April 2024, including deployment and 
demobilization of the ice camp. The submarine training and testing 
activities would occur over approximately 4 weeks during the 6-week 
period. The proposed IHA would be effective from February 1, 2024 
through April 30, 2024.

Geographic Region

    The ice camp would be established approximately 100-200 nautical 
miles (nmi) north of Prudhoe Bay, Alaska. The exact location of the 
camp cannot be identified ahead of time as required conditions (e.g., 
ice cover) cannot be forecasted until exercises are expected to 
commence. Prior to the establishment of the ice camp, reconnaissance 
flights would be conducted to locate suitable ice conditions. The 
reconnaissance flights would cover an area of approximately 70,374 
square kilometers (km\2\; 27,172 square miles (mi\2\)). The actual ice 
camp would be no more than 1.6 kilometers (km; 1 mi) in diameter 
(approximately 2 km\2\ (0.8 mi\2\) in area). The vast majority of 
submarine training and testing would occur near the ice camp, however 
some submarine training and testing may occur throughout the deep 
Arctic Ocean basin near the North Pole within the larger Navy Activity 
Study Area. Figure 1 shows the locations of the Navy Activity Study 
Area and Ice Camp Study Area, collectively referred to in this document 
as the ``ICEX24 Study Area''.
BILLING CODE 3510-22-P

[[Page 85246]]

[GRAPHIC] [TIFF OMITTED] TN07DE23.002

BILLING CODE 3510-22-C

Detailed Description of the Specified Activity

    The Navy proposes to conduct submarine training and testing 
activities, which includes the establishment of a tracking range and 
temporary ice camp, and research in the Arctic Ocean for six weeks 
beginning in February 2024. The activity proposed for 2024 and that is 
being evaluated for this proposed IHA--ICEX24--is part of a regular 
cycle of recurring training and testing activities that the Navy 
proposes to conduct in the Arctic, under which submarine and tracking 
range activities would be conducted biennially. Some of the submarine 
training and testing may occur throughout the deep Arctic Ocean basin 
near the North Pole, within the Navy Activity Study Area (Figure 1).

[[Page 85247]]

Additional information about the Navy's proposed training and testing 
activities in the Arctic is available in the Navy's 2023 Draft 
Supplemental Environmental Assessment/Overseas Environmental Assessment 
for the Ice Exercise Program, available at https://www.nepa.navy.mil/icex/. Only activities which may occur during ICEX24 are discussed in 
this section.
Ice Camp
    ICEX24 includes the deployment of a temporary camp situated on an 
ice floe. Reconnaissance flights to search for suitable ice conditions 
for the ice camp would depart from the public airport in Deadhorse, 
Alaska. The camp generally would consist of a command hut, dining hut, 
sleeping quarters, a powerhouse, runway, and helipad. The number of 
structures and tents would range from 15-20, and each tent is typically 
2 meters (m) by 6 m (6.6 ft by 19.7 ft) in size. The completed ice 
camp, including runway, would be approximately 1.6 km (1 mi) in 
diameter. Support equipment for the ice camp would include snowmobiles, 
gas-powered augers and saws (for boring holes through ice), and diesel 
generators. All ice camp materials, fuel, and food would be transported 
from Prudhoe Bay, Alaska, and delivered by air-drop from military 
transport aircraft (e.g., C-17 and C-130), or by landing at the ice 
camp runway (e.g., small twin-engine aircraft and military and 
commercial helicopters).
    A portable tracking range for submarine training and testing would 
be installed in the vicinity of the ice camp. Hydrophones, located on 
the ice and extending to 30 m (90.4 ft) below the ice, would be 
deployed by drilling or melting holes in the ice and lowering the cable 
down into the water column. Hydrophones would be linked remotely to the 
command hut. Additionally, tracking pingers would be configured aboard 
each submarine to continuously monitor the location of the submarines. 
Acoustic communications with the submarines would be used to coordinate 
the training and research schedule with the submarines. An underwater 
telephone would be used as a backup to the acoustic communications. The 
Navy plans to recover the hydrophones; however, if emergency 
demobilization is required, or the hydrophones are frozen in place and 
are unrecoverable, they would be left in place.
    Additional information about the ICEX24 ice camp is located in the 
2023 Draft Supplemental Environmental Assessment/Overseas Environmental 
Assessment for the Ice Exercise Program. We have carefully reviewed 
this information and determined that activities associated with the 
ICEX24 ice camp, including de minimis acoustic communications, would 
not result in incidental take of marine mammals.
Submarine Activities
    Submarine activities associated with ICEX24 generally would entail 
safety maneuvers and active sonar use. The safety maneuvers and sonar 
use are similar to submarine activities conducted in other undersea 
environments and are being conducted in the Arctic to test their 
performance in a cold environment. Submarine training and testing 
involves active acoustic transmissions, which have the potential to 
harass marine mammals. The Navy categorizes acoustic sources into 
``bins'' based on frequency, source level, and mode of usage (U.S. 
Department of the Navy, 2013). The acoustic transmissions associated 
with submarine training fall within bins HF1 (hull-mounted submarine 
sonars that produce high-frequency (greater than 10 kHz but less than 
200 kHz) signals) and M3 (mid-frequency (1-10 kHz) acoustic modems 
greater than 190 dB re 1 [micro]Pa) as defined in the Navy's Phase III 
at-sea environmental documentation (see Section 3.0.3.3.1, Acoustic 
Stressors, of the 2018 AFTT Final Environmental Impact Statement/
Overseas Environmental Impact Statement, available at https://www.nepa.navy.mil/AFTT-Phase-III/). The specifics of ICEX24 submarine 
acoustic sources are classified, including the parameters associated 
with the designated bins. Details of source use for submarine training 
are also classified. Any ICEX-specific acoustic sources not captured 
under one of the at-sea bins were modeled using source-specific 
parameters.
    Aspects of submarine training and testing activities other than 
active acoustic transmissions are fully analyzed within the 2023 Draft 
Supplemental Environmental Assessment/Overseas Environmental Assessment 
for the Ice Exercise Program. We have carefully reviewed and discussed 
with the Navy these other aspects, such as vessel use, and determined 
that aspects of submarine training and testing other than active 
acoustic transmissions would not result in take of marine mammals. 
These other aspects are therefore not discussed further, with the 
exception of potential vessel strike, which is discussed in the 
Potential Effects of Specified Activities on Marine Mammals and Their 
Habitat section.
Research Activities
    Personnel and equipment proficiency testing and multiple research 
and development activities would be conducted as part of ICEX24. 
Unmanned underwater vehicle testing and various acoustic/communication 
sources (i.e., echosounders, and transducers) involve active acoustic 
transmissions, which have the potential to harass marine mammals. Most 
acoustic transmissions that would be used in research activities for 
ICEX24 are considered de minimis. The Navy has defined de minimis 
sources as having the following parameters: low source levels, narrow 
beams, downward directed transmission, short pulse lengths, frequencies 
above (outside) known marine mammal hearing ranges, or some combination 
of these factors (U.S. Department of the Navy, 2013). NMFS reviewed the 
Navy's analysis and conclusions on de minimis sources and finds them 
complete and supportable. Parameters for scientific devices with active 
acoustics, including de minimis sources, are included in table 1. 
Additional information about ICEX24 research activities is located in 
table 1-1 of the Navy's IHA application as well as table 2-2 of the 
2023 Draft Supplemental Environmental Assessment/Overseas Environmental 
Assessment for the Ice Exercise Program, and elsewhere in that 
document. The possibility of vessel strikes caused by use of unmanned 
underwater vehicles during ICEX24 is discussed in the Potential Effects 
of Vessel Strike subsection within the Potential Effects of Specified 
Activities on Marine Mammals and Their Habitat section.

                                            Table 1--Parameters for Scientific Devices With Active Acoustics
--------------------------------------------------------------------------------------------------------------------------------------------------------
        Research institution               Source name        Frequency range (kHz)    Source level (dB)         Pulse length           Source type
--------------------------------------------------------------------------------------------------------------------------------------------------------
Woods Hole Oceanic Institute.......  LRAUV+................  10 and 25.............  185 or less..........  14 and 3000 ms.......  Unmanned Underwater
                                                                                                                                    Vehicle.
Naval Postgraduate School..........  Echosounder...........  38 to 200.............  221..................  0.5 ms...............  Sonar.

[[Page 85248]]

 
Massachusetts Institute of           Echosounder...........  115 and 200...........  227 or less..........  1 ms.................  Sonar.
 Technology Lincoln Lab.
Naval Postgraduate School..........  Geospectrum M72,        0.13, 0.8, and 5......  190 or less..........  maximum length         Transducer.
                                      Geospectrum M71, ITC                                                   sequence of 20 min
                                      1007.                                                                  on and 40 min off.
--------------------------------------------------------------------------------------------------------------------------------------------------------
Note: dB = decibels; kHz = kilohertz; LRAUV = Long Range Autonomous Underwater Vehicle; min = minutes; ms = millisecond(s).

    Proposed mitigation, monitoring, and reporting measures are 
described in detail later in this document (please see Proposed 
Mitigation and Proposed Monitoring and Reporting).

Description of Marine Mammals in the Area of Specified Activities

    Sections 3 and 4 of the application summarize available information 
regarding status and trends, distribution and habitat preferences, and 
behavior and life history of the potentially affected species. NMFS 
fully considered all of this information, and we refer the reader to 
these descriptions, instead of reprinting the information. Additional 
information regarding population trends and threats may be found in 
NMFS' Stock Assessment Reports (SARs; https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments) and 
more general information about these species (e.g., physical and 
behavioral descriptions) may be found on NMFS' website (https://www.fisheries.noaa.gov/find-species).
    Table 2 lists all species or stocks for which take is expected and 
proposed to be authorized for this activity, and summarizes information 
related to the population or stock, including regulatory status under 
the MMPA and Endangered Species Act (ESA) and potential biological 
removal (PBR), where known. PBR is defined by the MMPA as the maximum 
number of animals, not including natural mortalities, that may be 
removed from a marine mammal stock while allowing that stock to reach 
or maintain its optimum sustainable population (as described in NMFS' 
SARs). While no serious injury or mortality is anticipated or proposed 
to be authorized here, PBR and annual serious injury and mortality from 
anthropogenic sources are included here as gross indicators of the 
status of the species or stocks and other threats.
    Marine mammal abundance estimates presented in this document 
represent the total number of individuals that make up a given stock or 
the total number estimated within a particular study or survey area. 
NMFS' stock abundance estimates for most species represent the total 
estimate of individuals within the geographic area, if known, that 
comprises that stock. For some species, this geographic area may extend 
beyond U.S. waters. All managed stocks in this region are assessed in 
NMFS' U.S. Alaska SARs (Young et al. 2023). All values presented in 
table 2 are the most recent available at the time of publication and 
are available online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessments.

                        Table 2--Species Likely Impacted by the Specified Activities \1\
----------------------------------------------------------------------------------------------------------------
                                                                           Stock abundance
                                                                ESA/MMP a     (CV, Nmin,
         Common name          Scientific name       Stock        status;     most recent       PBR     Annual M/
                                                                strategic     abundance                  SI \4\
                                                                (Y/N) \2\    survey) \3\
----------------------------------------------------------------------------------------------------------------
Ringed Seal.................  Pusa hispida...  Arctic.........  T, D, Y    UND \5\ (UND,          UND      6,459
                                                                            UND, 2013).
----------------------------------------------------------------------------------------------------------------
\1\ Information on the classification of marine mammal species can be found on the web page for The Society for
  Marine Mammalogy's Committee on Taxonomy (https://marinemammalscience.org/science-and-publications/list-marine-mammal-species-subspecies/; Committee on Taxonomy (2022)).
\2\ Endangered Species Act (ESA) status: Endangered (E), Threatened (T)/MMPA status: Depleted (D). Under the
  MMPA, a strategic stock is one for which the level of direct human-caused mortality exceeds PBR or which is
  determined to be declining and likely to be listed under the ESA within the foreseeable future. Any species or
  stock listed under the ESA is automatically designated under the MMPA as depleted and as a strategic stock.
\3\ NMFS marine mammal stock assessment reports online at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-stock-assessment-reports-region. CV is coefficient of variation; Nmin is the minimum
  estimate of stock abundance.
\4\ These values, found in NMFS's SARs, represent annual levels of human-caused mortality plus serious injury
  from all sources combined (e.g., commercial fisheries, ship strike). Annual M/SI often cannot be determined
  precisely and is in some cases presented as a minimum value or range. A CV associated with estimated mortality
  due to commercial fisheries is presented in some cases.
\5\ A reliable population estimate for the entire stock is not available. Using a sub-sample of data collected
  from the U.S portion of the Bering Sea, an abundance estimate of 171,418 ringed seals has been calculated, but
  this estimate does not account for availability bias due to seals in the water or in the shorefast ice zone at
  the time of the survey. The actual number of ringed seals in the U.S. portion of the Bering Sea is likely much
  higher. Using the Nmin based upon this negatively biased population estimate, the PBR is calculated to be
  4,755 seals, although this is also a negatively biased estimate.

    As indicated in table 2, ringed seals (with one managed stock) 
temporally and spatially co-occur with the activity to the degree that 
take is reasonably likely to occur. While beluga whales (Delphinapterus 
leucas), gray whales (Eschrichtius robustus), bowhead whales (Balaena 
mysticetus), and spotted seals (Phoca largha) may occur in the ICEX24 
Study Area, the temporal and/or spatial occurrence of these species is 
such that take is not expected to occur, and they are not discussed 
further beyond the explanation provided here. Bowhead whales are 
unlikely to occur in the ICEX24 Study Area between February and April, 
as they spend winter (December to April) in the northern Bering Sea and 
southern Chukchi Sea, and migrate north through the Chukchi Sea and 
Beaufort Sea during April and May (Young et al. 2023). On their spring 
migration, the earliest that bowhead whales reach Point Hope in the 
Chukchi Sea, well south of Point Barrow, is late March to mid-April 
(Braham et al. 1980). Although the ice camp location is not known with 
certainty, the distance between Point Barrow and the closest edge of 
the Ice Camp Study Area is over 200 km (124.3 mi). The distance between 
Point Barrow and the closest edge of the Navy Activity Study Area is 
over 50 km (31 mi), and the distance between Point Barrow and Point 
Hope is an additional 525 km (326.2 mi; straight line distance); 
accordingly, bowhead whales are unlikely to occur in the ICEX24 Study 
Area before ICEX24 activities conclude. Beluga whales follow a 
migration pattern similar to

[[Page 85249]]

bowhead whales. They typically overwinter in the Bering Sea and migrate 
north during the spring to the eastern Beaufort Sea where they spend 
the summer and early fall months (Young et al. 2023). Though the beluga 
whale migratory path crosses through the ICEX24 Study Area, they are 
unlikely to occur in the ICEX24 Study Area between February and April. 
(Of note, the ICEX24 Study Area does overlap the northernmost portion 
of the North Bering Strait, East Chukchi, West Beaufort Sea beluga 
whale migratory BIA (April and May), though the data support for this 
BIA is low, the boundary certainty is low, and the importance score is 
moderate. Given the spring migratory direction, the northernmost 
portion of the BIA is likely more important later in the April and May 
period, and overlap with this BIA does not imply that belugas are 
likely to be in the ICEX24 Study Area during the Navy's activities.) 
Gray whales feed primarily in the Beaufort Sea, Chukchi Sea, and 
Northwestern Bering Sea during the summer and fall, but migrate south 
to winter in Baja California lagoons (Young et al. 2023). Typically, 
northward migrating gray whales do not reach the Bering Sea before May 
or June (Frost and Karpovich 2008), after the ICEX24 activities would 
occur, and several hundred kilometers south of the ICEX24 Study Area. 
Further, gray whales are primarily bottom feeders (Swartz et al. 2006) 
in water less than 60 m (196.9 ft) deep (Pike 1962). Therefore, on the 
rare occasion that a gray whale does overwinter in the Beaufort Sea 
(Stafford et al. 2007), we would expect an overwintering individual to 
remain in shallow water over the continental shelf where it could feed. 
Therefore, gray whales are not expected to occur in the ICEX24 Study 
Area during the ICEX24 activity period. Spotted seals may also occur in 
the ICEX24 Study Area during summer and fall, but they are not expected 
to occur in the ICEX24 Study Area during the ICEX24 timeframe (Muto et 
al. 2020).
    Further, while the Navy initially requested take of bearded seals 
(Erignathus barbatus), which do occur in the ICEX24 Study Area during 
the project timeframe, NMFS does not expect that bearded seals would 
occur in the areas near the ice camp or where submarine activities 
involving active acoustics would occur, and therefore incidental take 
is not anticipated to occur and has not been proposed for 
authorization. Bearded seals are not discussed further beyond the 
explanation provided here. The Navy anticipates that the ice camp would 
be established 100-200 nmi (185-370 km) north of Prudhoe Bay in water 
depths of 800 m (2,625 ft) or more, and also that submarine training 
and testing activities would occur in water depths of 800 m (2,625 ft) 
or more. Although acoustic data indicate that some bearded seals remain 
in the Beaufort Sea year round (MacIntyre et al. 2013, 2015; Jones et 
al. 2014), satellite tagging data (Boveng and Cameron 2013; ADF&G 2017) 
show that large numbers of bearded seals move south in fall/winter with 
the advancing ice edge to spend the winter in the Bering Sea, 
confirming previous visual observations (Burns and Frost 1979; Frost et 
al. 2008; Cameron and Boveng 2009). The southward movement of bearded 
seals in the fall means that very few individuals are expected to occur 
along the Beaufort Sea continental shelf in February through April, the 
timeframe for ICEX24 activities. The northward spring migration through 
the Bering Strait, begins in mid-April (Burns and Frost 1979).
    In the event some bearded seals were to remain in the Beaufort Sea 
during the season when ICEX24 activities will occur, the most probable 
area in which bearded seals might occur during winter months is along 
the continental shelf. Bearded seals feed extensively on benthic 
invertebrates (e.g., clams, gastropods, crabs, shrimp, bottom-dwelling 
fish; Quakenbush et al. 2011; Cameron et al. 2010) and are typically 
found in water depths of 200 m (656 ft) or less (Burns 1970). The 
Bureau of Ocean Energy Management (BOEM) conducted an aerial survey 
from June through October that covered the shallow Beaufort and Chukchi 
Sea shelf waters and observed bearded seals from Point Barrow to the 
border of Canada (Clarke et al. 2015). The farthest from shore that 
bearded seals were observed was the waters of the continental slope 
(though this study was conducted outside of the ICEX24 time frame). The 
Navy anticipates that the ice camp will be established 185-370 km (100-
200 nmi) north of Prudhoe Bay in water depths of 800 m (2,625 ft) or 
more. The continental shelf near Prudhoe Bay is approximately 55 nmi 
(100 km) wide. Therefore, even if the ice camp were established at the 
closest estimated distance (100 nmi from Prudhoe Bay), it would still 
be approximately 45 nmi (83 km) distant from habitat potentially 
occupied by bearded seals. Empirical evidence has not shown responses 
to sonar that would constitute take beyond a few km from an acoustic 
source, and therefore, NMFS and the Navy conservatively set a distance 
cutoff of 10 km (6.2 mi). Regardless of the source level at that 
distance, take is not estimated to occur beyond 10 km (6.2 mi) from the 
source. Although bearded seals occur 20 to 100 nmi (37 to 185 km) 
offshore during spring (Simpkins et al. 2003, Bengtson et al. 2005), 
they feed heavily on benthic organisms (Hamilton et al. 2018; Hjelset 
et al. 1999; Fedoseev 1965), and during winter bearded seals are 
expected to select habitats where food is abundant and easily 
accessible to minimize the energy required to forage and maximize 
energy reserves in preparation for whelping, lactation, mating, and 
molting. Bearded seals are not known to dive as deep as 800 m (2,625 
ft) to forage (Boveng and Cameron, 2013; Cameron and Boveng 2009; 
Cameron et al. 2010; Gjertz et al. 2000; Kovacs 2002), and it is highly 
unlikely that they would occur near the ice camp or where the submarine 
activities would be conducted. This conclusion is supported by the fact 
that the Navy did not visually observe or acoustically detect bearded 
seals during the 2020 or 2022 ice exercises.
    In addition, the polar bear (Ursus maritimus) may be found in the 
ICEX24 Study Area. However, polar bears are managed by the U.S. Fish 
and Wildlife Service and are not considered further in this document.

Ringed Seal

    Ringed seals are the most common pinniped in the ICEX24 Study Area 
and have wide distribution in seasonally and permanently ice-covered 
waters of the Northern Hemisphere (North Atlantic Marine Mammal 
Commission 2004), though the status of the Arctic stock of ringed seals 
is unknown (Young et al. 2023). Throughout their range, ringed seals 
have an affinity for ice-covered waters and are well adapted to 
occupying both shore-fast and pack ice (Kelly 1988c). Ringed seals can 
be found further offshore than other pinnipeds since they can maintain 
breathing holes in ice thickness greater than 2 m (6.6 ft; Smith and 
Stirling 1975). Breathing holes are maintained by ringed seals' sharp 
teeth and claws on their fore flippers. They remain in contact with ice 
most of the year and use it as a platform for molting in late spring to 
early summer, for pupping and nursing in late winter to early spring, 
and for resting at other times of the year (Young et al. 2023).
    Ringed seals have at least two distinct types of subnivean lairs: 
haul-out lairs and birthing lairs (Smith and Stirling 1975). Haul-out 
lairs are typically single-chambered and offer protection from 
predators and cold weather. Birthing lairs are larger, multi-

[[Page 85250]]

chambered areas that are used for pupping in addition to protection 
from predators. Ringed seals pup on both land-fast ice as well as 
stable pack ice. Lentfer (1972) found that ringed seals north of 
Barrow, Alaska (which would be west of the ice camp), build their 
subnivean lairs on the pack ice near pressure ridges. They are also 
assumed to occur within the sea ice in the proposed ice camp area. 
Ringed seals excavate subnivean lairs in drifts over their breathing 
holes in the ice, in which they rest, give birth, and nurse their pups 
for 5-9 weeks during late winter and spring (Chapskii 1940; McLaren 
1958; Smith and Stirling 1975). Snow depths of at least 50-65 
centimeters (cm; 19.7-25.6 in) are required for functional birth lairs 
(Kelly 1988b; Lydersen 1998; Lydersen and Gjertz 1986; Smith and 
Stirling 1975), and such depths typically occur only where 20-30 cm 
(7.9-11.8 in) or more of snow has accumulated on flat ice and then 
drifted along pressure ridges or ice hummocks (Hammill 2008; Lydersen 
et al. 1990; Lydersen and Ryg 1991; Smith and Lydersen 1991). Ringed 
seal birthing season typically begins in March, but the majority of 
births occur in early April. About a month after parturition, mating 
begins in late April and early May.
    In Alaskan waters, during winter and early spring when sea ice is 
at its maximal extent, ringed seals are abundant in the northern Bering 
Sea, Norton and Kotzebue Sounds, and throughout the Chukchi and 
Beaufort Seas (Frost 1985; Kelly 1988c), including in the ICEX24 Study 
Area. Passive acoustic monitoring (PAM) of ringed seals from a high-
frequency recording package deployed at a depth of 240 m (787 ft) in 
the Chukchi Sea, 120 km (74.6 mi) north-northwest of Barrow, Alaska, 
detected ringed seals in the area between mid- December and late May 
over a four year study (Jones et al. 2014). With the onset of the fall 
freeze, ringed seal movements become increasingly restricted and seals 
will either move west and south with the advancing ice pack, with many 
seals dispersing throughout the Chukchi and Bering Seas, or remain in 
the Beaufort Sea (Crawford et al. 2012; Frost and Lowry 1984; Harwood 
et al. 2012). Kelly et al. (2010a) tracked home ranges for ringed seals 
in the subnivean period (using shorefast ice); the size of the home 
ranges varied from less than 1 km\2\ (0.4 mi\2\) up to 27.9 km\2\ (10.8 
mi\2\; median of 0.62 km\2\ (0.2 mi\2\) for adult males and 0.65 km\2\ 
(0.3 mi\2\) for adult females). Most (94 percent) of the home ranges 
were less than 3 km\2\ (1.2 mi\2\) during the subnivean period (Kelly 
et al. 2010a). Near large polynyas, ringed seals maintain ranges up to 
7,000 km\2\ (2.702.7 mi\2\) during winter and 2,100 km\2\ (810 mi\2\) 
during spring (Born et al. 2004). Some adult ringed seals return to the 
same small home ranges they occupied during the previous winter (Kelly 
et al. 2010a). The size of winter home ranges can vary by up to a 
factor of 10 depending on the amount of fast ice; seal movements were 
more restricted during winters with extensive fast ice, and were much 
less restricted where fast ice did not form at high levels (Harwood et 
al. 2015). Ringed seals may occur within the ICEX24 Study Area 
throughout the year and during the proposed specified activities.
    Since June 1, 2018, elevated ice seal strandings (bearded, ringed 
and spotted seals) have occurred in the Bering and Chukchi seas in 
Alaska. This event was declared an Unusual Mortality Event (UME), but 
is currently considered non-active and is pending closure. Given that 
the UME is non-active, it is not discussed further in this document.

Critical Habitat

    Critical habitat for the ringed seal was designated in May 2022 and 
includes marine waters within one specific area in the Bering, Chukchi, 
and Beaufort Seas (87 FR 19232; April 1, 2022). Essential features 
established by NMFS for conservation of the ringed seal are (1) snow-
covered sea ice habitat suitable for the formation and maintenance of 
subnivean birth lairs used for sheltering pups during whelping and 
nursing, which is defined as waters 3 m (9.8 ft) or more in depth 
(relative to Mean Lower Low Water (MLLW)) containing areas of seasonal 
landfast (shorefast) ice or dense, stable pack ice, which have 
undergone deformation and contain snowdrifts of sufficient depth to 
form and maintain birth lairs (typically at least 54 cm (21.3 in) 
deep); (2) sea ice habitat suitable as a platform for basking and 
molting, which is defined as areas containing sea ice of 15 percent or 
more concentration in waters 3 m (9.8 ft) or more in depth (relative to 
MLLW); and (3) primary prey resources to support Arctic ringed seals, 
which are defined to be small, often schooling, fishes, in particular, 
Arctic cod (Boreogadus saida), saffron cod (Eleginus gracilis), and 
rainbow smelt (Osmerus dentex), and small crustaceans, in particular, 
shrimps and amphipods.
    The proposed ice camp study area was excluded from the ringed seal 
critical habitat because the benefits of exclusion due to national 
security impacts outweighed the benefits of inclusion of this area (87 
FR 19232; April 1, 2022). However, as stated in NMFS' final rule for 
the Designation of Critical Habitat for the Arctic Subspecies of the 
Ringed Seal (87 FR 19232; April 1, 2022), the area proposed for 
exclusion contains one or more of the essential features of the Arctic 
ringed seal's critical habitat, although data are limited to inform 
NMFS' assessment of the relative value of this area to the conservation 
of the species. As noted above, a portion of the ringed seal critical 
habitat overlaps the larger proposed ICEX24 Study Area. However, as 
described later and in more detail in the Potential Effects of 
Specified Activities on Marine Mammals and Their Habitat section, we do 
not anticipate physical impacts to any marine mammal habitat as a 
result of the Navy's ICEX activities, including impacts to ringed seal 
sea ice habitat suitable as a platform for basking and molting and 
impacts on prey availability. Further, this proposed IHA includes 
mitigation measures, as described in the Proposed Mitigation section, 
which would minimize or prevent impacts to sea ice habitat suitable for 
the formation and maintenance of subnivean birth lairs.

Marine Mammal Hearing

    Hearing is the most important sensory modality for marine mammals 
underwater, and exposure to anthropogenic sound can have deleterious 
effects. To appropriately assess the potential effects of exposure to 
sound, it is necessary to understand the frequency ranges marine 
mammals are able to hear. Not all marine mammal species have equal 
hearing capabilities (e.g., Richardson et al., 1995; Wartzok and 
Ketten, 1999; Au and Hastings, 2008). To reflect this, Southall et al. 
(2007, 2019) recommended that marine mammals be divided into hearing 
groups based on directly measured (behavioral or auditory evoked 
potential techniques) or estimated hearing ranges (behavioral response 
data, anatomical modeling, etc.). Note that no direct measurements of 
hearing ability have been successfully completed for mysticetes (i.e., 
low-frequency cetaceans). Subsequently, NMFS (2018) described 
generalized hearing ranges for these marine mammal hearing groups. 
Generalized hearing ranges were chosen based on the approximately 65 
decibels (dB) threshold from the normalized composite audiograms, with 
the exception for lower limits for low-frequency cetaceans where the 
lower bound was deemed to be biologically implausible and the lower 
bound from Southall et al. (2007) retained. Marine mammal hearing 
groups and their

[[Page 85251]]

associated hearing ranges are provided in table 3.

                  Table 3--Marine Mammal Hearing Groups
                              [NMFS, 2018]
------------------------------------------------------------------------
           Hearing group                 Generalized hearing range *
------------------------------------------------------------------------
Low-frequency (LF) cetaceans         7 Hz to 35 kHz.
 (baleen whales).
Mid-frequency (MF) cetaceans         150 Hz to 160 kHz.
 (dolphins, toothed whales, beaked
 whales, bottlenose whales).
High-frequency (HF) cetaceans (true  275 Hz to 160 kHz.
 porpoises, Kogia, river dolphins,
 Cephalorhynchid, Lagenorhynchus
 cruciger & L. australis).
Phocid pinnipeds (PW) (underwater)   50 Hz to 86 kHz.
 (true seals).
Otariid pinnipeds (OW) (underwater)  60 Hz to 39 kHz.
 (sea lions and fur seals).
------------------------------------------------------------------------
* Represents the generalized hearing range for the entire group as a
  composite (i.e., all species within the group), where individual
  species' hearing ranges are typically not as broad. Generalized
  hearing range chosen based on ~65 dB threshold from normalized
  composite audiogram, with the exception for lower limits for LF
  cetaceans (Southall et al. 2007) and PW pinniped (approximation).

    The pinniped functional hearing group was modified from Southall et 
al. (2007) on the basis of data indicating that phocid species have 
consistently demonstrated an extended frequency range of hearing 
compared to otariids, especially in the higher frequency range 
(Hemil[auml] et al., 2006; Kastelein et al., 2009; Reichmuth and Holt, 
2013).
    For more detail concerning these groups and associated frequency 
ranges, please see NMFS (2018) for a review of available information.

Potential Effects of Specified Activities on Marine Mammals and Their 
Habitat

    This section provides a discussion of the ways in which components 
of the specified activity may impact marine mammals and their habitat. 
The Estimated Take of Marine Mammals section later in this document 
includes a quantitative analysis of the number of individuals that are 
expected to be taken by this activity. The Negligible Impact Analysis 
and Determination section considers the content of this section, the 
Estimated Take of Marine Mammals section, and the Proposed Mitigation 
section, to draw conclusions regarding the likely impacts of these 
activities on the reproductive success or survivorship of individuals 
and whether those impacts are reasonably expected to, or reasonably 
likely to, adversely affect the species or stock through effects on 
annual rates of recruitment or survival.

Description of Sound Sources

    Here, we first provide background information on marine mammal 
hearing before discussing the potential effects of the use of active 
acoustic sources on marine mammals.
    Sound travels in waves, the basic components of which are 
frequency, wavelength, velocity, and amplitude. Frequency is the number 
of pressure waves that pass by a reference point per unit of time and 
is measured in Hz or cycles per second. Wavelength is the distance 
between two peaks of a sound wave; lower frequency sounds have longer 
wavelengths than higher frequency sounds and attenuate (decrease) more 
rapidly in shallower water. Amplitude is the height of the sound 
pressure wave or the `loudness' of a sound and is typically measured 
using the dB scale. A dB is the ratio between a measured pressure (with 
sound) and a reference pressure (sound at a constant pressure, 
established by scientific standards). It is a logarithmic unit that 
accounts for large variations in amplitude; therefore, relatively small 
changes in dB ratings correspond to large changes in sound pressure. 
When referring to sound pressure levels (SPLs; the sound force per unit 
area), sound is referenced in the context of underwater sound pressure 
to 1 microPascal ([mu]Pa). One pascal is the pressure resulting from a 
force of one newton exerted over an area of 1 square meter. The source 
level (SL) represents the sound level at a distance of 1 m from the 
source (referenced to 1 [mu]Pa). The received level is the sound level 
at the listener's position. Note that all underwater sound levels in 
this document are referenced to a pressure of 1 [micro]Pa.
    Root mean square (RMS) is the quadratic mean sound pressure over 
the duration of an impulse. RMS is calculated by squaring all of the 
sound amplitudes, averaging the squares, and then taking the square 
root of the average (Urick 1983). RMS accounts for both positive and 
negative values; squaring the pressures makes all values positive so 
that they may be accounted for in the summation of pressure levels 
(Hastings and Popper 2005). This measurement is often used in the 
context of discussing behavioral effects, in part because behavioral 
effects, which often result from auditory cues, may be better expressed 
through averaged units than by peak pressures.
    When underwater objects vibrate or activity occurs, sound-pressure 
waves are created. These waves alternately compress and decompress the 
water as the sound wave travels. Underwater sound waves radiate in all 
directions away from the source (similar to ripples on the surface of a 
pond), except in cases where the source is directional. The 
compressions and decompressions associated with sound waves are 
detected as changes in pressure by aquatic life and man-made sound 
receptors such as hydrophones.
    Even in the absence of sound from the specified activity, the 
underwater environment is typically loud due to ambient sound. Ambient 
sound is defined as environmental background sound levels lacking a 
single source or point (Richardson et al. 1995), and the sound level of 
a region is defined by the total acoustical energy being generated by 
known and unknown sources. These sources may include physical (e.g., 
waves, earthquakes, ice, atmospheric sound), biological (e.g., sounds 
produced by marine mammals, fish, and invertebrates), and anthropogenic 
sound (e.g., vessels, dredging, aircraft, construction). A number of 
sources contribute to ambient sound, including the following 
(Richardson et al. 1995):
    <bullet> Wind and waves: The complex interactions between wind and 
water surface, including processes such as breaking waves and wave-
induced bubble oscillations and cavitation, are a main source of 
naturally occurring ambient noise for frequencies between 200 Hz and 50 
kHz (Mitson, 1995). Under sea ice, noise generated by ice deformation 
and ice fracturing may be caused by thermal, wind, drift, and current 
stresses (Roth et al. 2012);
    <bullet> Precipitation: Sound from rain and hail impacting the 
water surface can become an important component of total noise at 
frequencies above 500 Hz, and possibly down to 100 Hz during quiet

[[Page 85252]]

times. In the ice-covered ICEX24 Study Area, precipitation is unlikely 
to impact ambient sound;
    <bullet> Biological: Marine mammals can contribute significantly to 
ambient noise levels, as can some fish and shrimp. The frequency band 
for biological contributions is from approximately 12 Hz to over 100 
kHz; and
    <bullet> Anthropogenic: Sources of ambient noise related to human 
activity include transportation (surface vessels and aircraft), 
dredging and construction, oil and gas drilling and production, seismic 
surveys, sonar, explosions, and ocean acoustic studies. Shipping noise 
typically dominates the total ambient noise for frequencies between 20 
and 300 Hz. In general, the frequencies of anthropogenic sounds are 
below 1 kHz and, if higher frequency sound levels are created, they 
attenuate rapidly (Richardson et al. 1995). Sound from identifiable 
anthropogenic sources other than the activity of interest (e.g., a 
passing vessel) is sometimes termed background sound, as opposed to 
ambient sound. Anthropogenic sources are unlikely to significantly 
contribute to ambient underwater noise during the late winter and early 
spring in the ICEX24 Study Area as most anthropogenic activities would 
not be active due to ice cover (e.g. seismic surveys, shipping; Roth et 
al. 2012).
    The sum of the various natural and anthropogenic sound sources at 
any given location and time--which comprise ``ambient'' or 
``background'' sound--depends not only on the source levels (as 
determined by current weather conditions and levels of biological and 
shipping activity) but also on the ability of sound to propagate 
through the environment. In turn, sound propagation is dependent on the 
spatially and temporally varying properties of the water column and sea 
floor, and is frequency-dependent. As a result of the dependence on a 
large number of varying factors, ambient sound levels can be expected 
to vary widely over both coarse and fine spatial and temporal scales. 
Sound levels at a given frequency and location can vary by 10-20 dB 
from day to day (Richardson et al. 1995). The result is that, depending 
on the source type and its intensity, sound from the specified activity 
may be a negligible addition to the local environment or could form a 
distinctive signal that may affect marine mammals.
    Underwater sounds fall into one of two general sound types: 
impulsive and non-impulsive (defined in the following paragraphs). The 
distinction between these two sound types is important because they 
have differing potential to cause physical effects, particularly with 
regard to hearing (e.g., Ward, 1997 in Southall et al. 2007). Please 
see Southall et al. (2007) for an in-depth discussion of these 
concepts.
    Impulsive sound sources (e.g., explosions, gunshots, sonic booms, 
impact pile driving) produce signals that are brief (typically 
considered to be less than one second), broadband, atonal transients 
(ANSI 1986; Harris 1998; NIOSH 1998; ISO 2016; ANSI 2005) and occur 
either as isolated events or repeated in some succession. Impulsive 
sounds are all characterized by a relatively rapid rise from ambient 
pressure to a maximal pressure value followed by a rapid decay period 
that may include a period of diminishing, oscillating maximal and 
minimal pressures, and generally have an increased capacity to induce 
physical injury as compared with sounds that lack these features. There 
are no pulsed sound sources associated with any planned ICEX24 
activities.
    Non-impulsive sounds can be tonal, narrowband, or broadband, brief 
or prolonged, and may be either continuous or non-continuous (ANSI 
1995; NIOSH 1998). Some of these non-impulsive sounds can be transient 
signals of short duration but without the essential properties of 
pulses (e.g., rapid rise time). Examples of non-impulsive sounds 
include those produced by vessels, aircraft, machinery operations such 
as drilling or dredging, vibratory pile driving, and active sonar 
sources (such as those planned for use by the Navy as part of the 
proposed ICEX24 activities) that intentionally direct a sound signal at 
a target that is reflected back in order to discern physical details 
about the target.
    Modern sonar technology includes a variety of sonar sensor and 
processing systems. In concept, the simplest active sonar emits sound 
waves, or ``pings,'' sent out in multiple directions, and the sound 
waves then reflect off of the target object in multiple directions. The 
sonar source calculates the time it takes for the reflected sound waves 
to return; this calculation determines the distance to the target 
object. More sophisticated active sonar systems emit a ping and then 
rapidly scan or listen to the sound waves in a specific area. This 
provides both distance to the target and directional information. Even 
more advanced sonar systems use multiple receivers to listen to echoes 
from several directions simultaneously and provide efficient detection 
of both direction and distance. In general, when sonar is in use, the 
sonar `pings' occur at intervals, referred to as a duty cycle, and the 
signals themselves are very short in duration. For example, sonar that 
emits a 1-second ping every 10 seconds has a 10 percent duty cycle. The 
Navy's most powerful hull-mounted mid-frequency sonar source used in 
ICEX activities typically emits a 1-second ping every 50 seconds 
representing a 2 percent duty cycle. The Navy utilizes sonar systems 
and other acoustic sensors in support of a variety of mission 
requirements.

Acoustic Impacts

    Please refer to the information provided previously regarding 
sound, characteristics of sound types, and metrics used in this 
document. Anthropogenic sounds cover a broad range of frequencies and 
sound levels and can have a range of highly variable impacts on marine 
life, from none or minor to potentially severe responses, depending on 
received levels, duration of exposure, behavioral context, and various 
other factors. The potential effects of underwater sound from active 
acoustic sources can include one or more of the following: temporary or 
permanent hearing impairment, non-auditory physical or physiological 
effects, behavioral disturbance, stress, and masking (Richardson et al. 
1995; Gordon et al. 2004; Nowacek et al. 2007; Southall et al. 2007; 
Gotz et al. 2009). The degree of effect is intrinsically related to the 
signal characteristics, received level, distance from the source, and 
duration of the sound exposure. In general, sudden, high level sounds 
can cause hearing loss, as can longer exposures to lower level sounds. 
Temporary or permanent loss of hearing will occur almost exclusively 
for noise within an animal's hearing range. In this section, we first 
describe specific manifestations of acoustic effects before providing 
discussion specific to the proposed activities in the next section.
    Permanent Threshold Shift--Marine mammals exposed to high-intensity 
sound, or to lower-intensity sound for prolonged periods, can 
experience hearing threshold shift (TS), which is the loss of hearing 
sensitivity at certain frequency ranges (Finneran 2015). TS can be 
permanent (PTS), in which case the loss of hearing sensitivity is not 
fully recoverable, or temporary (TTS), in which case the animal's 
hearing threshold would recover over time (Southall et al. 2007). 
Repeated sound exposure that leads to TTS could cause PTS. In severe 
cases of PTS, there can be total or partial deafness, while in most 
cases the animal has an impaired ability to hear sounds in specific 
frequency ranges (Kryter 1985).
    When PTS occurs, there is physical damage to the sound receptors in 
the ear (i.e., tissue damage), whereas TTS

[[Page 85253]]

represents primarily tissue fatigue and is reversible (Southall et al. 
2007). In addition, other investigators have suggested that TTS is 
within the normal bounds of physiological variability and tolerance and 
does not represent physical injury (e.g., Ward 1997). Therefore, NMFS 
does not consider TTS to constitute auditory injury.
    Relationships between TTS and PTS thresholds have not been studied 
in marine mammals--PTS data exists only for a single harbor seal (Phoca 
vitulina; Kastak et al. 2008)--but are assumed to be similar to those 
in humans and other terrestrial mammals. PTS typically occurs at 
exposure levels at least several dB above (a 40-dB threshold shift 
approximates PTS onset; e.g., Kryter et al. 1966; Miller, 1974) those 
inducing mild TTS (a 6-dB threshold shift approximates TTS onset; e.g., 
Southall et al. 2007). Based on data from terrestrial mammals, a 
precautionary assumption is that the PTS thresholds for impulse sounds 
(such as impact pile driving pulses as received close to the source) 
are at least six dB higher than the TTS threshold on a peak-pressure 
basis and PTS cumulative sound exposure level (SEL) thresholds are 15 
to 20 dB higher than TTS cumulative SEL thresholds (Southall et al. 
2007).
    Temporary Threshold Shift--TTS is the mildest form of hearing 
impairment that can occur during exposure to sound (Kryter, 1985). 
While experiencing TTS, the hearing threshold rises, and a sound must 
be at a higher level in order to be heard. In terrestrial and marine 
mammals, TTS can last from minutes or hours to days (in cases of strong 
TTS). In many cases, hearing sensitivity recovers rapidly after 
exposure to the sound ends.
    Marine mammal hearing plays a critical role in communication with 
conspecifics, and interpretation of environmental cues for purposes 
such as predator avoidance and prey capture. Depending on the degree 
(elevation of threshold in dB), duration (i.e., recovery time), and 
frequency range of TTS, and the context in which it is experienced, TTS 
can have effects on marine mammals ranging from discountable to 
serious. For example, a marine mammal may be able to readily compensate 
for a brief, relatively small amount of TTS in a non-critical frequency 
range that occurs during a time where ambient noise is lower and there 
are not as many competing sounds present. Alternatively, a larger 
amount and longer duration of TTS sustained during time when 
communication is critical for successful mother/calf interactions could 
have more serious impacts.
    Currently, TTS data only exist for four species of cetaceans 
(bottlenose dolphin (Tursiops truncatus), beluga whale, harbor porpoise 
(Phocoena phocoena), and Yangtze finless porpoise (Neophocoena 
asiaeorientalis)) and three species of pinnipeds (northern elephant 
seal (Mirounga angustirostris), harbor seal, and California sea lion 
(Zalophus californianus)) exposed to a limited number of sound sources 
(i.e., mostly tones and octave-band noise) in laboratory settings 
(Finneran 2015). TTS was not observed in trained spotted and ringed 
seals exposed to impulsive noise at levels matching previous 
predictions of TTS onset (Reichmuth et al. 2016). In general, harbor 
seals and harbor porpoises have a lower TTS onset than other measured 
pinniped or cetacean species. Additionally, the existing marine mammal 
TTS data come from a limited number of individuals within these 
species. There are no data available on noise-induced hearing loss for 
mysticetes. For summaries of data on TTS in marine mammals or for 
further discussion of TTS onset thresholds, please see Southall et al. 
(2007), Finneran and Jenkins (2012), and Finneran (2015).
    Behavioral effects--Behavioral disturbance may include a variety of 
effects, including subtle changes in behavior (e.g., minor or brief 
avoidance of an area or changes in vocalizations), more conspicuous 
changes in similar behavioral activities, and more sustained and/or 
potentially severe reactions, such as displacement from or abandonment 
of high-quality habitat. Behavioral responses to sound are highly 
variable and context-specific and any reactions depend on numerous 
intrinsic and extrinsic factors (e.g., species, state of maturity, 
experience, current activity, reproductive state, auditory sensitivity, 
time of day), as well as the interplay between factors (e.g., 
Richardson et al. 1995; Wartzok et al. 2003; Southall et al. 2007; 
Weilgart, 2007; Archer et al. 2010). Behavioral reactions can vary not 
only among individuals but also within an individual, depending on 
previous experience with a sound source, context, and numerous other 
factors (Ellison et al. 2012), and can vary depending on 
characteristics associated with the sound source (e.g., whether it is 
moving or stationary, number of sources, distance from the source). 
Please see Appendices B-C of Southall et al. (2007) for a review of 
studies involving marine mammal behavioral responses to sound.
    Habituation can occur when an animal's response to a stimulus wanes 
with repeated exposure, usually in the absence of unpleasant associated 
events (Wartzok et al. 2003). Animals are most likely to habituate to 
sounds that are predictable and unvarying. It is important to note that 
habituation is appropriately considered as a ``progressive reduction in 
response to stimuli that are perceived as neither aversive nor 
beneficial,'' rather than as, more generally, moderation in response to 
human disturbance (Bejder et al. 2009). The opposite process is 
sensitization, when an unpleasant experience leads to subsequent 
responses, often in the form of avoidance, at a lower level of 
exposure. As noted, behavioral state may affect the type of response. 
For example, animals that are resting may show greater behavioral 
change in response to disturbing sound levels than animals that are 
highly motivated to remain in an area for feeding (Richardson et al. 
1995; NRC 2003; Wartzok et al. 2003). Controlled experiments with 
captive marine mammals have shown pronounced behavioral reactions, 
including avoidance of loud sound sources (Ridgway et al. 1997; 
Finneran et al. 2003). Observed responses of wild marine mammals to 
loud impulsive sound sources (typically seismic airguns or acoustic 
harassment devices) have been varied but often consist of avoidance 
behavior or other behavioral changes suggesting discomfort (Morton and 
Symonds 2002; see also Richardson et al. 1995; Nowacek et al. 2007).
    Available studies show wide variation in response to underwater 
sound; therefore, it is difficult to predict specifically how any given 
sound in a particular instance might affect marine mammals perceiving 
the signal. If a marine mammal does react briefly to an underwater 
sound by changing its behavior or moving a small distance, the impacts 
of the change are unlikely to be significant to the individual, let 
alone the stock or population. However, if a sound source displaces 
marine mammals from an important feeding or breeding area for a 
prolonged period, impacts on individuals and populations could be 
significant (e.g., Lusseau and Bejder 2007; Weilgart 2007; NRC 2003). 
However, there are broad categories of potential response, which we 
describe in greater detail here, that include alteration of dive 
behavior, alteration of foraging behavior, effects to breathing, 
interference with or alteration of vocalization, avoidance, and flight.
    Changes in dive behavior can vary widely, and may consist of 
increased or decreased dive times and surface intervals as well as 
changes in the rates of ascent and descent during a dive (e.g., Frankel 
and Clark 2000; Costa et al.

[[Page 85254]]

2003; Ng and Leung, 2003; Nowacek et al. 2004; Goldbogen et al. 2013). 
Variations in dive behavior may reflect interruptions in biologically 
significant activities (e.g., foraging) or they may be of little 
biological significance. The impact of an alteration to dive behavior 
resulting from an acoustic exposure depends on what the animal is doing 
at the time of the exposure and the type and magnitude of the response.
    Disruption of feeding behavior can be difficult to correlate with 
anthropogenic sound exposure, so it is usually inferred by observed 
displacement from known foraging areas, the appearance of secondary 
indicators (e.g., bubble nets or sediment plumes), or changes in dive 
behavior. As for other types of behavioral response, the frequency, 
duration, and temporal pattern of signal presentation, as well as 
differences in species sensitivity, are likely contributing factors to 
differences in response in any given circumstance (e.g., Croll et al. 
2001; Nowacek et al. 2004; Madsen et al. 2006; Yazvenko et al. 2007). A 
determination of whether foraging disruptions incur fitness 
consequences would require information on or estimates of the energetic 
requirements of the affected individuals and the relationship between 
prey availability, foraging effort and success, and the life history 
stage of the animal.
    Variations in respiration naturally vary with different behaviors 
and alterations to breathing rate as a function of acoustic exposure 
can be expected to co-occur with other behavioral reactions, such as a 
flight response or an alteration in diving. However, respiration rates 
in and of themselves may be representative of annoyance or an acute 
stress response. Various studies have shown that respiration rates may 
either be unaffected or could increase, depending on the species and 
signal characteristics, again highlighting the importance in 
understanding species differences in the tolerance of underwater noise 
when determining the potential for impacts resulting from anthropogenic 
sound exposure (e.g., Kastelein et al. 2001, 2005b, 2006; Gailey et al. 
2007).
    Marine mammals vocalize for different purposes and across multiple 
modes, such as whistling, echolocation click production, calling, and 
singing. Changes in vocalization behavior in response to anthropogenic 
noise can occur for any of these modes and may result from a need to 
compete with an increase in background noise or may reflect increased 
vigilance or a startle response. For example, in the presence of 
potentially masking signals, humpback whales and killer whales have 
been observed to increase the length of their songs (Miller et al. 
2000; Fristrup et al. 2003; Foote et al. 2004), while right whales have 
been observed to shift the frequency content of their calls upward 
while reducing the rate of calling in areas of increased anthropogenic 
noise (Parks et al. 2007). In some cases, animals may cease sound 
production during production of aversive signals (Bowles et al. 1994).
    Avoidance is the displacement of an individual from an area or 
migration path as a result of the presence of a sound or other 
stressors, and is one of the most obvious manifestations of disturbance 
in marine mammals (Richardson et al. 1995). For example, gray whales 
are known to change direction--deflecting from customary migratory 
paths--in order to avoid noise from seismic surveys (Malme et al. 
1984). Avoidance may be short-term, with animals returning to the area 
once the noise has ceased (e.g., Bowles et al. 1994; Goold, 1996; 
Morton and Symonds, 2002; Gailey et al. 2007). Longer-term displacement 
is possible, however, which may lead to changes in abundance or 
distribution patterns of the affected species in the affected region if 
habituation to the presence of the sound does not occur (e.g., 
Blackwell et al. 2004; Bejder et al. 2006).
    A flight response is a dramatic change in normal movement to a 
directed and rapid movement away from the perceived location of a sound 
source. The flight response differs from other avoidance responses in 
the intensity of the response (e.g., directed movement, rate of 
travel). Relatively little information on flight responses of marine 
mammals to anthropogenic signals exist, although observations of flight 
responses to the presence of predators have occurred (Connor and 
Heithaus 1996). The result of a flight response could range from brief, 
temporary exertion and displacement from the area where the signal 
provokes flight to, in extreme cases, marine mammal strandings (Evans 
and England 2001). However, it should be noted that response to a 
perceived predator does not necessarily invoke flight (Ford and Reeves 
2008), and whether individuals are solitary or in groups may influence 
the response.
    Behavioral disturbance can also impact marine mammals in more 
subtle ways. Increased vigilance may result in costs related to 
diversion of focus and attention (i.e., when a response consists of 
increased vigilance, it may come at the cost of decreased attention to 
other critical behaviors such as foraging or resting). These effects 
have generally not been demonstrated for marine mammals, but studies 
involving fish and terrestrial animals have shown that increased 
vigilance may substantially reduce feeding rates (e.g., Beauchamp and 
Livoreil, 1997; Fritz et al. 2002; Purser and Radford 2011). In 
addition, chronic disturbance can cause population declines through 
reduction of fitness (e.g., decline in body condition) and subsequent 
reduction in reproductive success, survival, or both (e.g., Harrington 
and Veitch 1992; Daan et al. 1996; Bradshaw et al. 1998). However, 
Ridgway et al. (2006) reported that increased vigilance in bottlenose 
dolphins exposed to sound over a five-day period did not cause any 
sleep deprivation or stress effects.
    Many animals perform vital functions, such as feeding, resting, 
traveling, and socializing, on a diel cycle (24-hour cycle). Disruption 
of such functions resulting from reactions to stressors such as sound 
exposure are more likely to be significant if they last more than one 
diel cycle or recur on subsequent days (Southall et al. 2007). 
Consequently, a behavioral response lasting less than one day and not 
recurring on subsequent days is not considered particularly severe 
unless it could directly affect reproduction or survival (Southall et 
al. 2007). Note that there is a difference between multi-day 
substantive behavioral reactions and multi-day anthropogenic 
activities. For example, just because an activity lasts for multiple 
days does not necessarily mean that individual animals are either 
exposed to activity-related stressors for multiple days or, further, 
exposed in a manner resulting in sustained multi-day substantive 
behavioral responses.
    For non-impulsive sounds (i.e., similar to the sources used during 
the proposed specified activities), data suggest that exposures of 
pinnipeds to received levels between 90 and 140 dB re 1 [mu]Pa do not 
elicit strong behavioral responses; no data were available for 
exposures at higher received levels for Southall et al. (2007) to 
include in the severity scale analysis. Reactions of harbor seals were 
the only available data for which the responses could be ranked on the 
severity scale. For reactions that were recorded, the majority (17 of 
18 individuals/groups) were ranked on the severity scale as a 4 
(defined as moderate change in movement, brief shift in group 
distribution, or moderate change in vocal behavior) or lower; the 
remaining response was ranked as a 6 (defined as minor or moderate 
avoidance of the sound source). Additional data on hooded seals 
(Cystophora cristata) indicate avoidance

[[Page 85255]]

responses to signals above 160-170 dB re 1 [mu]Pa (Kvadsheim et al. 
2010), and data on gray seals (Halichoerus grypus) and harbor seals 
indicate avoidance response at received levels of 135-144 dB re 1 
[mu]Pa (G[ouml]tz et al. 2010). In each instance where food was 
available, which provided the seals motivation to remain near the 
source, habituation to the signals occurred rapidly. In the same study, 
it was noted that habituation was not apparent in wild seals where no 
food source was available (G[ouml]tz et al. 2010). This implies that 
the motivation of the animal is necessary to consider in determining 
the potential for a reaction. In one study that aimed to investigate 
the under-ice movements and sensory cues associated with under-ice 
navigation of ice seals, acoustic transmitters (60-69 kHz at 159 dB re 
1 [mu]Pa at 1 m) were attached to ringed seals (Wartzok et al. 1992a; 
Wartzok et al. 1992b). An acoustic tracking system then was installed 
in the ice to receive the acoustic signals and provide real-time 
tracking of ice seal movements. Although the frequencies used in this 
study are at the upper limit of ringed seal hearing, the ringed seals 
appeared unaffected by the acoustic transmissions, as they were able to 
maintain normal behaviors (e.g., finding breathing holes).
    Seals exposed to non-impulsive sources with a received sound 
pressure level within the range of calculated exposures for ICEX 
activities (142-193 dB re 1 [mu]Pa), have been shown to change their 
behavior by modifying diving activity and avoidance of the sound source 
(G[ouml]tz et al. 2010; Kvadsheim et al. 2010). Although a minor change 
to a behavior may occur as a result of exposure to the sources in the 
proposed specified activities, these changes would be within the normal 
range of behaviors for the animal (e.g., the use of a breathing hole 
further from the source, rather than one closer to the source, would be 
within the normal range of behavior; Kelly et al. 1988).
    Adult ringed seals spend up to 20 percent of the time in subnivean 
lairs during the winter season (Kelly et al. 2010a). Ringed seal pups 
spend about 50 percent of their time in the lair during the nursing 
period (Lydersen and Hammill 1993). During the warm season ringed seals 
haul out on the ice. In a study of ringed seal haulout activity by Born 
et al. (2002), ringed seals spent 25-57 percent of their time hauled 
out in June, which is during their molting season. Ringed seal lairs 
are typically used by individual seals (haulout lairs) or by a mother 
with a pup (birthing lairs); large lairs used by many seals for hauling 
out are rare (Smith and Stirling 1975). If the non-impulsive acoustic 
transmissions are heard and are perceived as a threat, ringed seals 
within subnivean lairs could react to the sound in a similar fashion to 
their reaction to other threats, such as polar bears (their primary 
predators). Responses of ringed seals to a variety of human-induced 
sounds (e.g., helicopter noise, snowmobiles, dogs, people, and seismic 
activity) have been variable; some seals entered the water and some 
seals remained in the lair. However, according to Kelly et al. (1988), 
in all instances in which observed seals departed lairs in response to 
noise disturbance, they subsequently reoccupied the lair.
    Ringed seal mothers have a strong bond with their pups and may 
physically move their pups from the birth lair to an alternate lair to 
avoid predation, sometimes risking their lives to defend their pups 
from potential predators (Smith 1987). If a ringed seal mother 
perceives the proposed acoustic sources as a threat, the network of 
multiple birth and haulout lairs allows the mother and pup to move to a 
new lair (Smith and Hammill 1981; Smith and Stirling 1975). The 
acoustic sources from these proposed specified activities are not 
likely to impede a ringed seal from finding a breathing hole or lair, 
as captive seals have been found to primarily use vision to locate 
breathing holes and no effect to ringed seal vision would occur from 
the acoustic disturbance (Elsner et al. 1989; Wartzok et al. 1992a). It 
is anticipated that a ringed seal would be able to relocate to a 
different breathing hole relatively easily without impacting their 
normal behavior patterns.
    Stress responses--An animal's perception of a threat may be 
sufficient to trigger stress responses consisting of some combination 
of behavioral responses, autonomic nervous system responses, 
neuroendocrine responses, or immune responses (e.g., Seyle 1950; Moberg 
2000). In many cases, an animal's first and sometimes most economical 
(in terms of energetic costs) response is behavioral avoidance of the 
potential stressor. Autonomic nervous system responses to stress 
typically involve changes in heart rate, blood pressure, and 
gastrointestinal activity. These responses have a relatively short 
duration and may or may not have a significant long-term effect on an 
animal's fitness.
    Neuroendocrine stress responses often involve the hypothalamus-
pituitary-adrenal system. Virtually all neuroendocrine functions that 
are affected by stress--including immune competence, reproduction, 
metabolism, and behavior--are regulated by pituitary hormones. Stress-
induced changes in the secretion of pituitary hormones have been 
implicated in failed reproduction, altered metabolism, reduced immune 
competence, and behavioral disturbance (e.g., Moberg, 1987; Blecha, 
2000). Increases in the circulation of glucocorticoids are also equated 
with stress (Romano et al. 2004).
    The primary distinction between stress (which is adaptive and does 
not normally place an animal at risk) and ``distress'' is the cost of 
the response. During a stress response, an animal uses glycogen stores 
that can be quickly replenished once the stress is alleviated. In such 
circumstances, the cost of the stress response would not pose serious 
fitness consequences. However, when an animal does not have sufficient 
energy reserves to satisfy the energetic costs of a stress response, 
energy resources must be diverted from other functions. This state of 
distress will last until the animal replenishes its energetic reserves 
sufficient to restore normal function.
    Relationships between these physiological mechanisms, animal 
behavior, and the costs of stress responses are well-studied through 
controlled experiments and for both laboratory and free-ranging animals 
(e.g., Holberton et al. 1996; Hood et al. 1998; Jessop et al. 2003; 
Krausman et al. 2004; Lankford et al. 2005). Stress responses due to 
exposure to anthropogenic sounds or other stressors and their effects 
on marine mammals have also been reviewed (Fair and Becker, 2000; 
Romano et al. 2002b) and, more rarely, studied in wild populations 
(e.g., Romano et al. 2002a). These and other studies lead to a 
reasonable expectation that some marine mammals will experience 
physiological stress responses upon exposure to acoustic stressors and 
that it is possible that some of these would be classified as 
``distress.'' In addition, any animal experiencing TTS would likely 
also experience stress responses (NRC, 2003).
    Auditory masking--Sound can disrupt behavior through masking, or 
interfering with, an animal's ability to detect, recognize, or 
discriminate between acoustic signals of interest (e.g., those used for 
intraspecific communication and social interactions, prey detection, 
predator avoidance, navigation) (Richardson et al. 1995). Masking 
occurs when the receipt of a sound is interfered with by another 
coincident sound at similar frequencies and at similar or higher 
intensity, and may occur whether the sound is natural (e.g., snapping 
shrimp, wind, waves,

[[Page 85256]]

precipitation) or anthropogenic (e.g., shipping, sonar, seismic 
exploration) in origin. The ability of a noise source to mask 
biologically important sounds depends on the characteristics of both 
the noise source and the signal of interest (e.g., signal-to-noise 
ratio, temporal variability, direction), in relation to each other and 
to an animal's hearing abilities (e.g., sensitivity, frequency range, 
critical ratios, frequency discrimination, directional discrimination, 
age or TTS hearing loss), and existing ambient noise and propagation 
conditions.
    Under certain circumstances, marine mammals experiencing 
significant masking could also be impaired from maximizing their 
performance fitness in survival and reproduction. Therefore, when the 
coincident (masking) sound is anthropogenic, it may be considered 
harassment when disrupting or altering critical behaviors. It is 
important to distinguish TTS and PTS, which persist after the sound 
exposure, from masking, which occurs during the sound exposure. Because 
masking (without resulting in TS) is not associated with abnormal 
physiological function, it is not considered a physiological effect, 
but rather a potential behavioral effect.
    The frequency range of the potentially masking sound is important 
in determining any potential behavioral impacts. For example, low-
frequency signals may have less effect on high-frequency echolocation 
sounds produced by odontocetes but are more likely to affect detection 
of mysticete communication calls and other potentially important 
natural sounds such as those produced by surf and some prey species. 
The masking of communication signals by anthropogenic noise may be 
considered as a reduction in the communication space of animals (e.g., 
Clark et al. 2009) and may result in energetic or other costs as 
animals change their vocalization behavior (e.g., Miller et al. 2000; 
Foote et al. 2004; Parks et al. 2007b; Di Iorio and Clark, 2009; Holt 
et al. 2009). Masking can be reduced in situations where the signal and 
noise come from different directions (Richardson et al. 1995), through 
amplitude modulation of the signal, or through other compensatory 
behaviors (Houser and Moore, 2014). Masking can be tested directly in 
captive species (e.g., Erbe 2008), but in wild populations it must be 
either modeled or inferred from evidence of masking compensation. There 
are few studies addressing real-world masking sounds likely to be 
experienced by marine mammals in the wild (e.g., Branstetter et al. 
2013).
    Masking affects both senders and receivers of acoustic signals and 
can potentially have long-term chronic effects on marine mammals at the 
population level as well as at the individual level. Low-frequency 
ambient sound levels have increased by as much as 20 dB (more than 
three times in terms of SPL) in the world's ocean from pre-industrial 
periods, with most of the increase from distant commercial shipping 
(Hildebrand 2009). All anthropogenic sound sources, but especially 
chronic and lower-frequency signals (e.g., from vessel traffic), 
contribute to elevated ambient sound levels, thus intensifying masking.
    Potential Effects of Sonar on Prey--Ringed seals feed on marine 
invertebrates and fish. Marine invertebrates occur in the world's 
oceans, from warm shallow waters to cold deep waters, and are the 
dominant animals in all habitats of the ICEX24 Study Area. Although 
most species are found within the benthic zone, marine invertebrates 
can be found in all zones (sympagic (within the sea ice), pelagic (open 
ocean), or benthic (bottom dwelling)) of the Beaufort Sea (Josefson et 
al. 2013). The diverse range of species include oysters, crabs, worms, 
ghost shrimp, snails, sponges, sea fans, isopods, and stony corals 
(Chess and Hobson 1997; Dugan et al. 2000; Proctor et al. 1980).
    Hearing capabilities of invertebrates are largely unknown (Lovell 
et al. 2005; Popper and Schilt 2008). Outside of studies conducted to 
test the sensitivity of invertebrates to vibrations, very little is 
known on the effects of anthropogenic underwater noise on invertebrates 
(Edmonds et al. 2016). While data are limited, research suggests that 
some of the major cephalopods and decapods may have limited hearing 
capabilities (Hanlon 1987; Offutt 1970), and may hear only low-
frequency (less than 1 kHz) sources (Offutt 1970), which is most likely 
within the frequency band of biological signals (Hill 2009). In a 
review of crustacean sensitivity of high amplitude underwater noise by 
Edmonds et al. (2016), crustaceans may be able to hear the frequencies 
at which they produce sound, but it remains unclear which noises are 
incidentally produced and if there are any negative effects from 
masking them. Acoustic signals produced by crustaceans range from low 
frequency rumbles (20-60 Hz) to high frequency signals (20-55 kHz) 
(Henninger and Watson 2005; Patek and Caldwell 2006; Staaterman et al. 
2016). Aquatic invertebrates that can sense local water movements with 
ciliated cells include cnidarians, flatworms, segmented worms, 
urochordates (tunicates), mollusks, and arthropods (Budelmann 1992a, 
1992b; Popper et al. 2001). Some aquatic invertebrates have specialized 
organs called statocysts for determination of equilibrium and, in some 
cases, linear or angular acceleration. Statocysts allow an animal to 
sense movement and may enable some species, such as cephalopods and 
crustaceans, to be sensitive to water particle movements associated 
with sound (Goodall et al. 1990; Hu et al. 2009; Kaifu et al. 2008; 
Montgomery et al. 2006; Popper et al. 2001; Roberts and Breithaupt 
2016; Salmon 1971). Because any acoustic sensory capabilities, if 
present at all, are limited to detecting water motion, and water 
particle motion near a sound source falls off rapidly with distance, 
aquatic invertebrates are probably limited to detecting nearby sound 
sources rather than sound caused by pressure waves from distant 
sources.
    Studies of sound energy effects on invertebrates are few, and 
identify only behavioral responses. Non-auditory injury, PTS, TTS, and 
masking studies have not been conducted for invertebrates. Both 
behavioral and auditory brainstem response studies suggest that 
crustaceans may sense frequencies up to 3 kHz, but best sensitivity is 
likely below 200 Hz (Goodall et al. 1990; Lovell et al. 2005; Lovell et 
al. 2006). Most cephalopods likely sense low-frequency sound below 1 
kHz, with best sensitivities at lower frequencies (Budelmann 2010; 
Mooney et al. 2010; Offutt 1970). A few cephalopods may sense higher 
frequencies up to 1,500 Hz (Hu et al. 2009).
    It is expected that most marine invertebrates would not sense the 
frequencies of the sonar associated with the proposed specified 
activities. Most marine invertebrates would not be close enough to 
active sonar systems to potentially experience impacts to sensory 
structures. Any marine invertebrate capable of sensing sound may alter 
its behavior if exposed to sonar. Although acoustic transmissions 
produced during the proposed specified activities may briefly impact 
individuals, intermittent exposures to sonar are not expected to impact 
survival, growth, recruitment, or reproduction of widespread marine 
invertebrate populations.
    The fish species located in the ICEX24 Study Area include those 
that are closely associated with the deep ocean habitat of the Beaufort 
Sea. Nearly 250 marine fish species have been described in the Arctic, 
excluding the larger parts of the sub-Arctic Bering, Barents, and 
Norwegian Seas (Mecklenburg et al. 2011). However, only about 30 are

[[Page 85257]]

known to occur in the Arctic waters of the Beaufort Sea (Christiansen 
and Reist 2013). Largely because of the difficulty of sampling in 
remote, ice-covered seas, many high-Arctic fish species are known only 
from rare or geographically patchy records (Mecklenburg et al. 2011). 
Aquatic systems of the Arctic undergo extended seasonal periods of ice 
cover and other harsh environmental conditions. Fish inhabiting such 
systems must be biologically and ecologically adapted to surviving such 
conditions. Important environmental factors that Arctic fish must 
contend with include reduced light, seasonal darkness, ice cover, low 
biodiversity, and low seasonal productivity.
    All fish have two sensory systems to detect sound in the water: the 
inner ear, which functions very much like the inner ear in other 
vertebrates, and the lateral line, which consists of a series of 
receptors along the fish's body (Popper and Fay 2010; Popper et al. 
2014). The inner ear generally detects relatively higher-frequency 
sounds, while the lateral line detects water motion at low frequencies 
(below a few hundred Hz) (Hastings and Popper 2005). Lateral line 
receptors respond to the relative motion between the body surface and 
surrounding water; this relative motion, however, only takes place very 
close to sound sources and most fish are unable to detect this motion 
at more than one to two body lengths distance away (Popper et al. 
2014). Although hearing capability data only exist for fewer than 100 
of the approximately 32,000 fish species known to exist, current data 
suggest that most species of fish detect sounds from 50 to 1,000 Hz, 
with few fish hearing sounds above 4 kHz (Popper 2008). It is believed 
that most fish have their best hearing sensitivity from 100 to 400 Hz 
(Popper 2003). Permanent hearing loss has not been documented in fish. 
A study by Halvorsen et al. (2012) found that for temporary hearing 
loss or similar negative impacts to occur, the noise needed to be 
within the fish's individual hearing frequency range; external factors, 
such as developmental history of the fish or environmental factors, may 
result in differing impacts to sound exposure in fish of the same 
species. The sensory hair cells of the inner ear in fish can regenerate 
after they are damaged, unlike in mammals where sensory hair cells loss 
is permanent (Lombarte et al. 1993; Smith et al. 2006). As a 
consequence, any hearing loss in fish may be as temporary as the 
timeframe required to repair or replace the sensory cells that were 
damaged or destroyed (Smith et al. 2006), and no permanent loss of 
hearing in fish would result from exposure to sound.
    Fish species in the ICEX24 Study Area are expected to hear the low-
frequency sources associated with the proposed specified activities, 
but most are not expected to detect the higher-frequency sounds. Only a 
few fish species are able to detect mid-frequency sonar above 1 kHz and 
could have behavioral reactions or experience auditory masking during 
these activities. These effects are expected to be transient, and long-
term consequences for the population are not expected. Fish with 
hearing specializations capable of detecting high-frequency sounds are 
not expected to be within the ICEX24 Study Area. If hearing specialists 
were present, they would have to be in close vicinity to the source to 
experience effects from the acoustic transmission. Human-generated 
sound could alter the behavior of a fish in a manner that would affect 
its way of living, such as where it tries to locate food or how well it 
can locate a potential mate; behavioral responses to loud noise could 
include a startle response, such as the fish swimming away from the 
source, the fish ``freezing'' and staying in place, or scattering 
(Popper 2003). Auditory masking could also interfere with a fish's 
ability to hear biologically relevant sounds, inhibiting the ability to 
detect both predators and prey, and impacting schooling, mating, and 
navigating (Popper 2003). If an individual fish comes into contact with 
low-frequency acoustic transmissions and is able to perceive the 
transmissions, they are expected to exhibit short-term behavioral 
reactions, when initially exposed to acoustic transmissions, which 
would not significantly alter breeding, foraging, or populations. 
Overall effects to fish from ICEX24 active sonar sources would be 
localized, temporary, and infrequent.
    Effects of Acoustics on Physical and Foraging Habitat--Unless the 
sound source is stationary and/or continuous over a long duration in 
one area, neither of which applies to ICEX24 activities, the effects of 
the introduction of sound into the environment are generally considered 
to have a less severe impact on marine mammal habitat compared to any 
physical alteration of the habitat. Acoustic exposures are not expected 
to result in long-term physical alteration of the water column or 
bottom topography as the occurrences are of limited duration and would 
occur intermittently. Acoustic transmissions also would have no 
structural impact to subnivean lairs in the ice. Furthermore, since ice 
dampens acoustic transmissions (Richardson et al. 1995) the level of 
sound energy that reaches the interior of a subnivean lair would be 
less than that ensonifying water under surrounding ice. For these 
reasons, it is unlikely that the Navy's acoustic activities in the 
ICEX24 Study Area would have any effect on marine mammal habitat.

Potential Effects of Vessel Strike

    Because ICEX24 would occur only when there is ice coverage and 
conditions are appropriate to establish an ice camp on an ice floe, no 
ships or smaller boats would be involved in the activity. Vessel use 
would be limited to submarines and unmanned underwater vehicles 
(hereafter referred to together as ``vessels'' unless noted 
separately). The potential for vessel strike during ICEX24 would 
therefore only arise from the use of submarines during training and 
testing activities, and the use of unmanned underwater vehicles during 
research activities. Depths at which vessels would operate during 
ICEX24 would overlap with known dive depths of ringed seals, which have 
been recorded to 300 m (984.3 ft) in depth (Gjertz et al. 2000; 
Lydersen 1991). Few authors have specifically described the responses 
of pinnipeds to vessels, and most of the available information on 
reactions to boats concerns pinnipeds hauled out on land or ice. No 
information is available on potential responses to submarines or 
unmanned underwater vehicles. Brueggeman et al. (1992) stated ringed 
seals hauled out on the ice showed short-term escape reactions when 
they were within 0.25-0.5 km (0.2-0.3 mi) from a vessel; ringed seals 
would likely show similar reactions to submarines and unmanned 
underwater vehicles, decreasing the likelihood of vessel strike during 
ICEX24 activities.
    The Navy has kept strike records for over 20 years and has no 
records of individual pinnipeds being struck by a vessel as a result of 
Navy activities and, further, the smaller size and maneuverability of 
pinnipeds make a vessel strike unlikely. Also, NMFS has never received 
any reports indicating that pinnipeds have been struck by vessels of 
any type. Review of additional sources of information in the form of 
worldwide ship strike records shows little evidence of strikes of 
pinnipeds from the shipping sector. Further, a review of seal stranding 
data from Alaska found that during 2020, 9 ringed seal strandings were 
recorded by the Alaska Marine Mammal Stranding Network. Within the 
Arctic region of Alaska, 7 ringed seal strandings were

[[Page 85258]]

recorded. Of the 9 strandings reported in Alaska (all regions 
included), none were found to be caused by vessel collisions (Savage 
2021).
    Vessel speed, size, and mass are all important factors in 
determining both the potential likelihood and impacts of a vessel 
strike to marine mammals (Conn and Silber, 2013; Gende et al. 2011; 
Silber et al. 2010; Vanderlaan and Taggart, 2007; Wiley et al. 2016). 
When submerged, submarines are generally slow moving (to avoid 
detection) and therefore marine mammals at depth with a submarine are 
likely able to avoid collision with the submarine. For most of the 
research and training and testing activities during the specified 
activity, submarine and unmanned underwater vehicle speeds would not 
typically exceed 10 knots during the time spent within the ICEX24 Study 
Area, which would lessen the already extremely unlikely chance of 
collisions with marine mammals, specifically ringed seals.
    Based on consideration of all this information, NMFS does not 
anticipate incidental take of marine mammals by vessel strike from 
submarines or unmanned underwater vehicles.

Other Non-Acoustic Impacts

    Deployment of the ice camp could potentially affect ringed seal 
habitat by physically damaging or crushing subnivean lairs, which could 
potentially result in ringed seal injury or mortality. March 1 is 
generally expected to be the onset of ice seal lairing season, and 
ringed seals typically construct lairs near pressure ridges. As 
described in the Proposed Mitigation section, the ice camp and runway 
would be established on a combination of first-year ice and multi-year 
ice without pressure ridges, which would minimize the possibility of 
physical impacts to subnivean lairs and habitat suitable for lairs. Ice 
camp deployment would begin mid-February, and be gradual, with activity 
increasing over the first five days. So in addition, this schedule 
would discourage seals from establishing birthing lairs in or near the 
ice camp, and would allow ringed seals to relocate outside of the ice 
camp area as needed, though both scenarios are unlikely as described 
below in this section. Personnel on on-ice vehicles would observe for 
marine mammals, and would follow established routes when available, to 
avoid potential disturbance of lairs and habitat suitable for lairs. 
Personnel on foot and operating on-ice vehicles would avoid deep snow 
drifts near pressure ridges, also to avoid potential lairs and habitat 
suitable for lairs. Implementation of these measures are expected to 
prevent ringed seal lairs from being crushed or damaged during ICEX24 
activities, and are expected to minimize any other potential impacts to 
sea ice habitat suitable for the formation of lairs. Given the proposed 
mitigation requirements, we also do not anticipate ringed seal injury 
or mortality as a result of damage to subnivean lairs.
    ICEX24 personnel would be actively conducting testing and training 
operations on the sea ice and would travel around the camp area, 
including the runway, on snowmobiles. Although the Navy does not 
anticipate observing any seals on the ice given the lack of 
observations during previous ice exercises (U.S. Navy, 2020), as a 
general matter, on-ice activities could cause a seal that would have 
otherwise built a lair in the area of an activity to be displaced and 
therefore, construct a lair in a different area outside of an activity 
area, or a seal could choose to relocate to a different existing lair 
outside of an activity area. However, in the case of the ice camp 
associated with ICEX24, displacement of seal lair construction or 
relocation to existing lairs outside of the ice camp area is unlikely, 
given the low average density of structures (the average ringed seal 
ice structure density in the vicinity of Prudhoe Bay, Alaska is 1.58 
structures per km\2\ (table 4)), the relative footprint of the Navy's 
planned ice camp (2 km\2\; 0.8 mi\2\), the lack of previous ringed seal 
observations on the ice during ICEX activities, and proposed mitigation 
requirements that would require the Navy to construct the ice camp and 
runway on first-year or multiyear ice without pressure ridges and would 
require personnel to avoid areas of deep snow drift or pressure ridges 
(see the Proposed Mitigation section for additional information about 
the proposed mitigation requirements). This measure, in combination 
with the other mitigation measures required for operation of the ice 
camp are expected to avoid impacts to the construction and use of 
ringed seal subnivean lairs, particularly given the already low average 
density of lairs, as described above.

              Table 4--Ringed Seal Ice Structure Density in the Vicinity of the Prudhoe Bay, Alaska
----------------------------------------------------------------------------------------------------------------
                                             Ice structure density
                   Year                      (structures per km\2\)                     Source
----------------------------------------------------------------------------------------------------------------
1982......................................                      3.6  Frost and Burns 1989.
1983......................................                     0.81  Kelly et al. 1986.
1999......................................                     0.71  Williams et al. 2001.
2000......................................                      1.2  Williams et al. 2001.
Average Density...........................                     1.58  ...........................................
----------------------------------------------------------------------------------------------------------------

    Given the required mitigation measures and the low density of 
ringed seals anticipated in the Ice Camp Study Area during ICEX24, we 
do not anticipate behavioral disturbance of ringed seals due to human 
presence.
    The Navy's activities would occur prior to the late spring to early 
summer ``basking period,'' which occurs between abandonment of the 
subnivean lairs and melting of the seasonal sea ice, and is when the 
seals undergo their annual molt (Kelly et al. 2010b). Given that the 
ice camp would be demobilized prior to the basking period, and the 
remainder of the Navy's activities occur below the sea ice, impacts to 
sea ice habitat suitable as a platform for basking and molting are not 
anticipated to result from the Navy's ICEX24 activities.
    Our preliminary determination of potential effects to the physical 
environment includes minimal possible impacts to marine mammals and 
their habitat from camp operation or deployment activities, given the 
proposed mitigation and the timing of the Navy's proposed activities. 
In addition, given the relatively short duration of submarine testing 
and training activities, the relatively small area that would be 
affected, and the lack of impacts to physical or foraging habitat, the 
proposed specified activities are not likely to have an adverse effect 
on prey species or marine mammal habitat, other than potential 
localized, temporary, and infrequent effects to fish as discussed 
above. Therefore, any impacts to ringed seals and their habitat, as 
discussed above in this section, are not expected to cause significant 
or

[[Page 85259]]

long-term consequences for individual ringed seals or the population. 
Please see the Negligible Impact Analysis and Determination section for 
additional discussion regarding the likely impacts of the Navy's 
activities on ringed seals, including the reproductive success or 
survivorship of individual ringed seals, and how those impacts on 
individuals are likely to impact the species or stock.

Estimated Take of Marine Mammals

    This section provides an estimate of the number of incidental takes 
proposed for authorization through this IHA, which will inform NMFS' 
consideration of the negligible impact determinations and impacts on 
subsistence uses.
    Harassment is the only type of take expected to result from these 
activities. For this military readiness activity, the MMPA defines 
``harassment'' as (i) Any act that injures or has the significant 
potential to injure a marine mammal or marine mammal stock in the wild 
(Level A harassment); or (ii) Any act that disturbs or is likely to 
disturb a marine mammal or marine mammal stock in the wild by causing 
disruption of natural behavioral patterns, including, but not limited 
to, migration, surfacing, nursing, breeding, feeding, or sheltering, to 
a point where the behavioral patterns are abandoned or significantly 
altered (Level B harassment).
    Authorized takes would be by Level B harassment only, in the form 
of behavioral reactions and/or TTS for individual marine mammals 
resulting from exposure to acoustic transmissions. Based on the nature 
of the activity, Level A harassment is neither anticipated nor proposed 
to be authorized. As described previously, no serious injury or 
mortality is anticipated or proposed to be authorized for this 
activity. Below we describe how the proposed take numbers are 
estimated.
    For acoustic impacts, generally speaking, we estimate take by 
considering: (1) acoustic thresholds above which NMFS believes the best 
available science indicates marine mammals will be behaviorally 
harassed or incur some degree of permanent hearing impairment; (2) the 
area or volume of water that will be ensonified above these levels in a 
day; (3) the density or occurrence of marine mammals within these 
ensonified areas; and, (4) the number of days of activities. We note 
that while these factors can contribute to a basic calculation to 
provide an initial prediction of potential takes, additional 
information that can qualitatively inform take estimates is also 
sometimes available (e.g., previous monitoring results or average group 
size). Below, we describe the factors considered here in more detail 
and present the take estimates.

Acoustic Thresholds

    NMFS recommends the use of acoustic thresholds that identify the 
received level of underwater sound above which exposed marine mammals 
would be reasonably expected to be behaviorally harassed (equated to 
Level B harassment) or to incur PTS of some degree (equated to Level A 
harassment).
    Level B Harassment--In coordination with NMFS, the Navy developed 
behavioral thresholds to support environmental analyses for the Navy's 
testing and training military readiness activities utilizing active 
sonar sources; these behavioral harassment thresholds are used here to 
evaluate the potential effects of the active sonar components of the 
proposed specified activities. Though significantly driven by received 
level, the onset of behavioral disturbance from anthropogenic noise 
exposure is also informed to varying degrees by other factors related 
to the source or exposure context (e.g., frequency, predictability, 
duty cycle, duration of the exposure, signal-to-noise ratio, distance 
to the source), the environment (e.g., bathymetry, other noises in the 
area, predators in the area), and the receiving animals (hearing, 
motivation, experience, demography, life stage, depth) and can be 
difficult to predict (e.g., Southall et al., 2007, 2021, Ellison et 
al., 2012).
    The Navy's Phase III proposed pinniped behavioral threshold was 
updated based on controlled exposure experiments on the following 
captive animals: Hooded seal, gray seal, and California sea lion 
(G[ouml]tz et al. 2010; Houser et al. 2013a; Kvadsheim et al. 2010). 
Overall exposure levels were 110-170 dB re 1 [mu]Pa for hooded seals, 
140-180 dB re 1 [mu]Pa for gray seals, and 125-185 dB re 1 [mu]Pa for 
California sea lions; responses occurred at received levels ranging 
from 125 to 185 dB re 1 [mu]Pa. However, the means of the response data 
were between 159 and 170 dB re 1 [mu]Pa. Hooded seals were exposed to 
increasing levels of sonar until an avoidance response was observed, 
while the grey seals were exposed first to a single received level 
multiple times, then an increasing received level. Each individual 
California sea lion was exposed to the same received level ten times. 
These exposure sessions were combined into a single response value, 
with an overall response assumed if an animal responded in any single 
session. Because these data represent a dose-response type relationship 
between received level and a response, and because the means were all 
tightly clustered, the Bayesian biphasic Behavioral Response Function 
for pinnipeds most closely resembles a traditional sigmoidal dose-
response function at the upper received levels and has a 50 percent 
probability of response at 166 dB re 1 [mu]Pa. Additionally, to account 
for proximity to the source discussed above and based on the best 
scientific information, a conservative distance of 10 km is used beyond 
which exposures would not constitute a take under the military 
readiness definition of Level B harassment.
    Level A harassment--NMFS' Technical Guidance for Assessing the 
Effects of Anthropogenic Sound on Marine Mammal Hearing (Version 2.0) 
(Technical Guidance, 2018) identifies dual criteria to assess auditory 
injury (Level A harassment) to five different marine mammal groups 
(based on hearing sensitivity) as a result of exposure to noise from 
two different types of sources (impulsive or non-impulsive). The Navy's 
activities include the use of non-impulsive (active sonar) sources.
    These thresholds are provided in the table below. The references, 
analysis, and methodology used in the development of the thresholds are 
described in NMFS' 2018 Technical Guidance, which may be accessed at: 
https://www.fisheries.noaa.gov/national/marine-mammal-protection/marine-mammal-acoustic-technical-guidance.
    For previous ICEXs, the Navy's PTS/TTS analysis began with 
mathematical modeling to predict the sound transmission patterns from 
Navy sources, including sonar. These data were then coupled with marine 
species distribution and abundance data to determine the sound levels 
likely to be received by various marine species. These criteria and 
thresholds were applied to estimate specific effects that animals 
exposed to Navy-generated sound may experience. For weighting function 
derivation, the most critical data required were TTS onset exposure 
levels as a function of exposure frequency. These values can be 
estimated from published literature by examining TTS as a function of 
sound exposure level (SEL) for various frequencies.
    Table 5 below provides the weighted criteria and thresholds used in 
previous ICEX analyses for estimating quantitative acoustic exposures 
of marine mammals from the specified activities.

[[Page 85260]]



  Table 5--Acoustic Thresholds Identifying the Onset of Behavioral Disturbance, TTS, and PTS for Non-Impulsive
                                                Sound Sources \1\
----------------------------------------------------------------------------------------------------------------
                                                                                   Physiological criteria
                                                            Behavioral     -------------------------------------
    Functional hearing group            Species              criteria       TTS threshold SEL  PTS threshold SEL
                                                                                (weighted)         (weighted)
----------------------------------------------------------------------------------------------------------------
Phocid Pinnipeds (Underwater)..  Ringed seal..........  Pinniped Dose       181 dB SEL         201 dB SEL
                                                         Response Function   cumulative.        cumulative.
                                                         \2\.
----------------------------------------------------------------------------------------------------------------
\1\ The threshold values provided are assumed for when the source is within the animal's best hearing
  sensitivity. The exact threshold varies based on the overlap of the source and the frequency weighting.
\2\ See Figure 6-1 in the Navy's IHA application.
Note: SEL thresholds in dB re: 1 [mu]Pa\2\ s.

Marine Mammal Occurrence and Take Calculation and Estimation

    In previous ICEX analyses, the Navy has performed a quantitative 
analysis to estimate the number of ringed seals that could be harassed 
by the underwater acoustic transmissions during the proposed specified 
activities using marine mammal density estimates (Kaschner et al. 2006 
and Kaschner 2004), marine mammal depth occurrence distributions (U.S 
Department of the Navy, 2017), oceanographic and environmental data, 
marine mammal hearing data, and criteria and thresholds for levels of 
potential effects. Given the lack of recent density estimates for the 
ICEX Study Area and the lack of ringed seal observations and acoustic 
detections during ICEXs in the recent past (described in further detail 
below), NMFS expects that the ringed seal density relied upon in 
previous ICEX analyses was an overestimate to a large degree, and that 
the resulting take estimates were likely overestimates as well. Please 
see the notice of the final IHA for ICEX 22 for additional information 
on that analysis (87 FR 7803; January 10, 2022).
    For ICEX24, rather than relying on a density estimate, the Navy 
estimated take of ringed seals based on an occurrence estimate of 
ringed seals within the ICEX Study Area. Ringed seal presence in the 
ICEX Study Area was obtained using sighting data from the Ocean 
Biodiversity Information System-Spatial Ecological Analysis of 
Megavertebrate Populations (OBIS-SEAMAP; Halpin et al. 2009). The ICEX 
Study Area was overlaid on the OBIS-SEAMAP ringed seal sightings map 
that included sightings for years 2000 to 2007 and 2013. Sighting data 
were only available for the mid-to-late summer and fall months. Due to 
the paucity of winter and spring data, the average number of individual 
ringed seals per year was assumed to be present in the ICEX Study Area 
during ICEX24; therefore, it is assumed that three ringed seals would 
be present in the ICEX Study Area.
    Table 6 provides range to effects for active acoustic sources 
proposed for ICEX24 to phocid pinniped-specific criteria. Phocids 
within these ranges would be predicted to receive the associated 
effect. Range to effects can be important information for predicting 
acoustic impacts, but also in determining adequate mitigation ranges to 
avoid higher level effects, especially physiological effects, to marine 
mammals.

                 Table 6--Range to Behavioral Disturbance, TTS, and PTS in the ICEX24 Study Area
----------------------------------------------------------------------------------------------------------------
                                                                              Range to effects (m)
                                                              --------------------------------------------------
                       Source/exercise                            Behavioral
                                                                 disturbance          TTS              PTS
----------------------------------------------------------------------------------------------------------------
Submarine Exercise...........................................      10,000 \a\            5,050          130 \b\
----------------------------------------------------------------------------------------------------------------
\a\ Empirical evidence has not shown responses to sonar that would constitute take beyond a few km from an
  acoustic source, which is why NMFS and the Navy conservatively set a distance cutoff of 10 km. Regardless of
  the source level at that distance, take is not estimated to occur beyond 10 km from the source.
\b\ The distance represents the range to effects for all ICEX24 activities.

    Though likely conservative given the size of the ICEX Study Area in 
comparison to the size of the anticipated Level B harassment zone 
(10,000 m), Navy estimated that three ringed seals may be taken by 
Level B harassment per day of activity within the ICEX Study Area. Navy 
anticipates conducting active acoustic transmissions on 42 days, and 
therefore requested 126 takes by Level B harassment of ringed seals (3 
seals per day x 42 days = 126 takes by Level B harassment; Table 7). 
NMFS concurs and proposes to authorize 126 takes by Level B harassment. 
Modeling for the three previous ICEXs (2018, 2020, and 2022), which 
employed similar acoustic sources, did not result in any estimated 
takes by PTS; therefore, particularly in consideration of the fact that 
total takes were likely overestimated for those ICEX activities given 
the density information used in the analyses (NMFS anticipates that the 
density of ringed seals is actually much lower) and the relatively 
small range to effects for PTS (130 m), the Navy did not request, and 
NMFS is not proposing to authorize, take by Level A harassment of 
ringed seal.

                Table 7--Quantitative Modeling Results of Potential Exposures for ICEX Activities
----------------------------------------------------------------------------------------------------------------
                                                                   Level B          Level A
                           Species                                harassment       harassment         Total
----------------------------------------------------------------------------------------------------------------
Ringed seal..................................................             126                0              126
----------------------------------------------------------------------------------------------------------------


[[Page 85261]]

    During monitoring for the 2018 IHA covering similar military 
readiness activities in the ICEX22 Study Area, the Navy did not 
visually observe or acoustically detect any marine mammals (U.S. Navy, 
2018). During monitoring for the 2020 IHA covering similar military 
readiness activities in the ICEX22 Study Area, the Navy also did not 
visually observe any marine mammals (U.S. Navy, 2020). Acoustic 
monitoring associated with the 2020 IHA did not detect any discernible 
marine mammal vocalizations (Henderson et al. 2021). The monitoring 
report states that ``there were a few very faint sounds that could have 
been (ringed seal) barks or yelps.'' However, these were likely not 
from ringed seals, given that ringed seal vocalizations are generally 
produced in series (Jones et al. 2014). Henderson et al. (2021) expect 
that these sounds were likely ice-associated or perhaps anthropogenic. 
While the distance at which ringed seals could be acoustically detected 
is not definitive, Henderson et al. (2021) states that Expendable 
Mobile ASW Training Targets (EMATTs) ``traveled a distance of 10 nmi 
(18.5 km) away and were detected the duration of the recordings; 
although ringed seal vocalization source levels are likely far lower 
than the sounds emitted by the EMATTs, this gives some idea of the 
potential detection radius for the cryophone. The periods when the 
surface anthropogenic activity is occurring in close proximity to the 
cryophone are dominated by those broadband noises due to the shallow 
hydrophone placement in ice (only 10 cm down), and any ringed seal 
vocalizations that were underwater could have been masked.'' During 
monitoring for the 2022 IHA covering similar military readiness 
activities in the ICEX24 Study Area, the Navy also did not visually 
observe any marine mammals (U.S. Navy, 2022). With the exception of PAM 
conducted during activities for mitigation purposes (no detections), 
PAM did not occur in 2022 because the ice camp ice flow broke up, and 
therefore, Navy had to relocate camp. Given the lost time, multiple 
research projects were canceled, including the under-ice PAM that the 
Naval Postgraduate School was planning to conduct.

Proposed Mitigation

    In order to issue an IHA under section 101(a)(5)(D) of the MMPA, 
NMFS must set forth the permissible methods of taking pursuant to the 
activity, and other means of effecting the least practicable impact on 
the species or stock and its habitat, paying particular attention to 
rookeries, mating grounds, and areas of similar significance, and on 
the availability of the species or stock for taking for certain 
subsistence uses. NMFS regulations require applicants for incidental 
take authorizations to include information about the availability and 
feasibility (economic and technological) of equipment, methods, and 
manner of conducting the activity or other means of effecting the least 
practicable adverse impact upon the affected species or stocks, and 
their habitat (50 CFR 216.104(a)(11)). The 2004 NDAA amended the MMPA 
as it relates to military readiness activities and the incidental take 
authorization process such that ``least practicable impact'' shall 
include consideration of personnel safety, practicality of 
implementation, and impact on the effectiveness of the military 
readiness activity.
    In evaluating how mitigation may or may not be appropriate to 
ensure the least practicable adverse impact on species or stocks and 
their habitat, as well as subsistence uses where applicable, NMFS 
considers two primary factors:
    (1) The manner in which, and the degree to which, the successful 
implementation of the measure(s) is expected to reduce impacts to 
marine mammals, marine mammal species or stocks, and their habitat, as 
well as subsistence uses. This considers the nature of the potential 
adverse impact being mitigated (likelihood, scope, range). It further 
considers the likelihood that the measure will be effective if 
implemented (probability of accomplishing the mitigating result if 
implemented as planned), the likelihood of effective implementation 
(probability implemented as planned); and
    (2) The practicability of the measures for applicant 
implementation, which may consider such things as cost, impact on 
operations, and, in the case of a military readiness activity, 
personnel safety, practicality of implementation, and impact on the 
effectiveness of the military readiness activity.
    The proposed IHA requires that appropriate personnel (including 
civilian personnel) involved in mitigation and training or testing 
activity reporting under the specified activities must complete Arctic 
Environmental and Safety Awareness Training. Modules include: Arctic 
Species Awareness and Mitigations, Environmental Considerations, 
Hazardous Materials Management, and General Safety.
    Further, the following general mitigation measures are required to 
prevent incidental take of ringed seals on the ice floe associated with 
the ice camp (further explanation of certain mitigation measures is 
provided in parentheses following the measure):
    <bullet> The ice camp and runway must be established on first-year 
and multi-year ice without pressure ridges. (This will minimize 
physical impacts to subnivean lairs and impacts to sea ice habitat 
suitable for lairs);
    <bullet> Ice camp deployment must begin no later than mid-February 
2024, and be gradual, with activity increasing over the first 5 days. 
Camp deployment must be completed by March 15, 2024. (Given that 
mitigation measures require that the ice camp and runway be established 
on first-year or multi-year ice without pressure ridges, as well as the 
average ringed seal lair density in the area, and the relative 
footprint of the Navy's planned ice camp (2 km\2\ 0.8 mi\2\), it is 
extremely unlikely that a ringed seal would build a lair in the 
vicinity of the ice camp. Additionally, based on the best available 
science, Arctic ringed seal whelping is not expected to occur prior to 
mid-March, and therefore, construction of the ice camp will be 
completed prior to whelping in the area of ICEX24. Further, as noted 
above, ringed seal lairs are not expected to occur in the ice camp 
study area, and therefore, NMFS does not expect ringed seals to 
relocate pups due to human disturbance from ice camp activities, 
including construction);
    <bullet> Personnel on all on-ice vehicles must observe for marine 
and terrestrial animals;
    <bullet> Snowmobiles must follow established routes, when 
available. On-ice vehicles must not be used to follow any animal, with 
the exception of actively deterring polar bears if the situation 
requires;
    <bullet> Personnel on foot and operating on-ice vehicles must avoid 
areas of deep snowdrifts near pressure ridges. (These areas are 
preferred areas for subnivean lair development);
    <bullet> Personnel must maintain a 100 m (328 ft) avoidance 
distance from all observed marine mammals; and
    <bullet> All material (e.g., tents, unused food, excess fuel) and 
wastes (e.g., solid waste, hazardous waste) must be removed from the 
ice floe upon completion of ICEX24 activities.
    The following mitigation measures are required for activities 
involving acoustic transmissions (further explanation of certain 
mitigation measures is provided in parentheses following the measure):
    <bullet> Personnel must begin passive acoustic monitoring (PAM) for 
vocalizing marine mammals 15 minutes prior to the start of activities 
involving active acoustic transmissions from

[[Page 85262]]

submarines. (This PAM would be conducted for the area around the 
submarine in real time by technicians on board the submarine.);
    <bullet> Personnel must delay active acoustic transmissions if a 
marine mammal is detected during pre-activity PAM and must shutdown 
active acoustic transmissions if a marine mammal is detected during 
acoustic transmissions; and
    <bullet> Personnel must not restart acoustic transmissions until 15 
minutes have passed with no marine mammal detections.
    Ramp up procedures for acoustic transmissions are not required as 
the Navy determined, and NMFS concurs, that they would result in 
impacts on military readiness and on the realism of training that would 
be impracticable.
    The following mitigation measures are required for aircraft 
activities to prevent incidental take of marine mammals due to the 
presence of aircraft and associated noise.
    <bullet> Fixed wing aircraft must operate at the highest altitudes 
practicable taking into account safety of personnel, meteorological 
conditions, and need to support safe operations of a drifting ice camp. 
Aircraft must not reduce altitude if a seal is observed on the ice. In 
general, cruising elevation must be 305 m (1,000 ft) or higher;
    <bullet> Unmanned Aircraft Systems (UAS) must maintain a minimum 
altitude of at least 15.2 m (50 ft) above the ice. They must not be 
used to track or follow marine mammals;
    <bullet> Helicopter flights must use prescribed transit corridors 
when traveling to or from Prudhoe Bay and the ice camp. Helicopters 
must not hover or circle above marine mammals or within 457 m (1,500 
ft) of marine mammals;
    <bullet> Aircraft must maintain a minimum separation distance of 
1.6 km (1 mi) from groups of 5 or more seals; and
    <bullet> Aircraft must not land on ice within 800 m (0.5 mi) of 
hauled-out seals.
    Based on our evaluation of the applicant's proposed measures, as 
well as other measures considered by NMFS, NMFS has preliminarily 
determined that the proposed mitigation measures provide the means of 
effecting the least practicable impact on the affected species or 
stocks and their habitat, paying particular attention to rookeries, 
mating grounds, and areas of similar significance.

Proposed Monitoring and Reporting

    In order to issue an IHA for an activity, section 101(a)(5)(D) of 
the MMPA states that NMFS must set forth requirements pertaining to the 
monitoring and reporting of such taking. The MMPA implementing 
regulations at 50 CFR 216.104(a)(13) indicate that requests for 
authorizations must include the suggested means of accomplishing the 
necessary monitoring and reporting that will result in increased 
knowledge of the species and of the level of taking or impacts on 
populations of marine mammals that are expected to be present while 
conducting the activities. Effective reporting is critical both to 
compliance as well as ensuring that the most value is obtained from the 
required monitoring.
    Monitoring and reporting requirements prescribed by NMFS should 
contribute to improved understanding of one or more of the following:
    <bullet> Occurrence of marine mammal species or stocks in the area 
in which take is anticipated (e.g., presence, abundance, distribution, 
density);
    <bullet> Nature, scope, or context of likely marine mammal exposure 
to potential stressors/impacts (individual or cumulative, acute or 
chronic), through better understanding of: (1) action or environment 
(e.g., source characterization, propagation, ambient noise); (2) 
affected species (e.g., life history, dive patterns); (3) co-occurrence 
of marine mammal species with the activity; or (4) biological or 
behavioral context of exposure (e.g., age, calving or feeding areas);
    <bullet> Individual marine mammal responses (behavioral or 
physiological) to acoustic stressors (acute, chronic, or cumulative), 
other stressors, or cumulative impacts from multiple stressors;
    <bullet> How anticipated responses to stressors impact either: (1) 
long-term fitness and survival of individual marine mammals; or (2) 
populations, species, or stocks;
    <bullet> Effects on marine mammal habitat (e.g., marine mammal prey 
species, acoustic habitat, or other important physical components of 
marine mammal habitat); and
    <bullet> Mitigation and monitoring effectiveness.
    The Navy has coordinated with NMFS to develop an overarching 
program, the Integrated Comprehensive Monitoring Program (ICMP), 
intended to coordinate marine species monitoring efforts across all 
regions and to allocate the most appropriate level and type of effort 
for each range complex based on a set of standardized objectives, and 
in acknowledgement of regional expertise and resource availability. The 
ICMP was created in direct response to Navy requirements established in 
various MMPA regulations and ESA consultations. As a framework 
document, the ICMP applies by regulation to those activities on ranges 
and operating areas for which the Navy is seeking or has sought 
incidental take authorizations.
    The ICMP is focused on Navy training and testing ranges where the 
majority of Navy activities occur regularly, as those areas have the 
greatest potential for being impacted by the Navy's activities. In 
comparison, ICEX is a short duration exercise that occurs approximately 
every other year. Due to the location and expeditionary nature of the 
ice camp, the number of personnel on site is extremely limited and is 
constrained by the requirement to be able to evacuate all personnel in 
a single day with small planes. As such, the Navy asserts that a 
dedicated ICMP monitoring project is not feasible as it would require 
additional personnel and equipment, and NMFS concurs. However, the Navy 
is exploring the potential of implementing an environmental DNA (eDNA) 
study on ice seals.
    Nonetheless, the Navy must conduct the following monitoring and 
reporting under the IHA. Ice camp personnel must generally monitor for 
marine mammals in the vicinity of the ice camp and record all 
observations of marine mammals, regardless of distance from the ice 
camp, as well as the additional data indicated below. Additionally, 
Navy personnel must conduct PAM during all active sonar use. Ice camp 
personnel must also maintain an awareness of the surrounding 
environment and document any observed marine mammals.
    In addition, the Navy is required to provide NMFS with a draft 
exercise monitoring report within 90 days of the conclusion of the 
specified activity. A final report must be prepared and submitted 
within 30 calendar days following receipt of any NMFS comments on the 
draft report. If no comments are received from NMFS within 30 calendar 
days of receipt of the draft report, the report shall be considered 
final. The report, at minimum, must include:
    <bullet> Marine mammal monitoring effort (dedicated hours);
    <bullet> Ice camp activities occurring during each monitoring 
period (e.g., construction, demobilization, safety watch, field 
parties);
    <bullet> Number of marine mammals detected;
    <bullet> Upon observation of a marine mammal, record the following 
information:
    [cir] Environmental conditions when animal was observed, including 
relevant weather conditions such as cloud cover,

[[Page 85263]]

snow, sun glare, and overall visibility, and estimated observable 
distance;
    [cir] Lookout location and ice camp activity at time of sighting 
(or location and activity of personnel who made observation, if 
observed outside of designated monitoring periods);
    [cir] Time and approximate location of sighting;
    [cir] Identification of the animal(s) (e.g., seal, or 
unidentified), also noting any identifying features;
    [cir] Distance and location of each observed marine mammal relative 
to the ice camp location for each sighting;
    [cir] Estimated number of animals (min/max/best estimate); and
    [cir] Description of any marine mammal behavioral observations 
(e.g., observed behaviors such as traveling), including an assessment 
of behavioral responses thought to have resulted from the activity 
(e.g., no response or changes in behavioral state such as ceasing 
feeding, changing direction, flushing).
    Also, all sonar usage will be collected via the Navy's Sonar 
Positional Reporting System database. The Navy is required to provide 
data regarding sonar use and the number of shutdowns during ICEX24 
activities in the Atlantic Fleet Training and Testing (AFTT) Letter of 
Authorization 2024 annual classified report. The Navy is also required 
to analyze any declassified underwater recordings collected during 
ICEX24 for marine mammal vocalizations and report that information to 
NMFS, including the types and nature of sounds heard (e.g., clicks, 
whistles, creaks, burst pulses, continuous, sporadic, strength of 
signal) and the species or taxonomic group (if determinable). This 
information will also be submitted to NMFS with the 2024 annual AFTT 
declassified monitoring report.
    Finally, in the event that personnel discover an injured or dead 
marine mammal, personnel must report the incident to OPR, NMFS and to 
the Alaska regional stranding network as soon as feasible. The report 
must include the following information:
    <bullet> Time, date, and location (latitude/longitude) of the first 
discovery (and updated location information if known and applicable);
    <bullet> Species identification (if known) or description of the 
animal(s) involved;
    <bullet> Condition of the animal(s) (including carcass condition if 
the animal is dead);
    <bullet> Observed behaviors of the animal(s), if alive;
    <bullet> If available, photographs or video footage of the 
animal(s); and
    <bullet> General circumstances under which the animal(s) was 
discovered (e.g., during submarine activities, observed on ice floe, or 
by transiting aircraft).

Negligible Impact Analysis and Determination

    NMFS has defined negligible impact as an impact resulting from the 
specified activity that cannot be reasonably expected to, and is not 
reasonably likely to, adversely affect the species or stock through 
effects on annual rates of recruitment or survival (50 CFR 216.103). A 
negligible impact finding is based on the lack of likely adverse 
effects on annual rates of recruitment or survival (i.e., population-
level effects). An estimate of the number of takes alone is not enough 
information on which to base an impact determination. In addition to 
considering estimates of the number of marine mammals that might be 
``taken'' through harassment, NMFS considers other factors, such as the 
likely nature of any impacts or responses (e.g., intensity, duration), 
the context of any impacts or responses (e.g., critical reproductive 
time or location, foraging impacts affecting energetics), as well as 
effects on habitat, and the likely effectiveness of the mitigation. We 
also assess the number, intensity, and context of estimated takes by 
evaluating this information relative to population status. Consistent 
with the 1989 preamble for NMFS' implementing regulations (54 FR 40338; 
September 29, 1989), the impacts from other past and ongoing 
anthropogenic activities are incorporated into this analysis via their 
impacts on the baseline (e.g., as reflected in the regulatory status of 
the species, population size and growth rate where known, ongoing 
sources of human-caused mortality, or ambient noise levels).
    Underwater acoustic transmissions associated with ICEX24, as 
outlined previously, have the potential to result in Level B harassment 
of ringed seals in the form of TTS and behavioral disturbance. No take 
by Level A harassment, serious injury, or mortality are anticipated to 
result from this activity. Further, at close ranges and high sound 
levels approaching those that could cause PTS, seals would likely avoid 
the area immediately around the sound source.
    NMFS anticipates that take of ringed seals by TTS could occur from 
the submarine activities. TTS is a temporary impairment of hearing and 
can last from minutes or hours to days (in cases of strong TTS). In 
many cases, however, hearing sensitivity recovers rapidly after 
exposure to the sound ends. This activity has the potential to result 
in only minor levels of TTS, and hearing sensitivity of affected 
animals would be expected to recover quickly. Though TTS may occur as 
indicated, the overall fitness of the impacted individuals is unlikely 
to be affected given the temporary nature of TTS and the minor levels 
of TTS expected from these activities. Negative impacts on the 
reproduction or survival of affected ring seals as well as impacts on 
the stock are not anticipated.
    Effects on individuals that are taken by Level B harassment by 
behavioral disturbance could include alteration of dive behavior, 
alteration of foraging behavior, effects to breathing, interference 
with or alteration of vocalization, avoidance, and flight. More severe 
behavioral responses are not anticipated due to the localized, 
intermittent use of active acoustic sources and mitigation using PAM, 
which would limit exposure to active acoustic sources. Most likely, 
individuals would be temporarily displaced by moving away from the 
sound source. As described previously in the Acoustic Impacts section, 
seals exposed to non-impulsive sources with a received sound pressure 
level within the range of calculated exposures, (142-193 dB re 1 
[mu]Pa), have been shown to change their behavior by modifying diving 
activity and avoidance of the sound source (G[ouml]tz et al. 2010; 
Kvadsheim et al. 2010). Although a minor change to a behavior may occur 
as a result of exposure to the sound sources associated with the 
proposed specified activity, these changes would be within the normal 
range of behaviors for the animal (e.g., the use of a breathing hole 
further from the source, rather than one closer to the source). 
Further, given the limited number of total instances of takes and the 
unlikelihood that any single individuals would be taken repeatedly, 
multiple times over sequential days, these takes are unlikely to impact 
the reproduction or survival of any individuals.
    The Navy's proposed activities are localized and of relatively 
short duration. While the total ICEX24 Study Area is large, the Navy 
expects that most activities would occur within the Ice Camp Study Area 
in relatively close proximity to the ice camp. The larger Navy Activity 
Study Area depicts the range where submarines may maneuver during the 
exercise. The ice camp would be in existence for up to 6 weeks with 
acoustic transmission occurring intermittently over approximately 4 
weeks.
    The project is not expected to have significant adverse effects on 
marine mammal habitat. The project activities are limited in time and 
would not

[[Page 85264]]

modify physical marine mammal habitat. While the activities may cause 
some fish to leave a specific area ensonified by acoustic 
transmissions, temporarily impacting marine mammals' foraging 
opportunities, these fish would likely return to the affected area. As 
such, the impacts to marine mammal habitat are not expected to cause 
significant or long-term negative consequences.
    For on-ice activity, Level A harassment, Level B harassment, 
serious injury, and mortality are not anticipated, given the nature of 
the activities, the lack of previous ringed seal observations, and the 
mitigation measures NMFS has proposed to include in the IHA. The ringed 
seal pupping season on the ice lasts for 5 to 9 weeks during late 
winter and spring. As stated in the Potential Effects of Specified 
Activities on Marine Mammals and Their Habitat section, March 1 is 
generally expected to be the onset of ice seal lairing season. The ice 
camp and runway would be established on first-year ice or multi-year 
ice without pressure ridges, as ringed seals tend to build their lairs 
near pressure ridges. Ice camp deployment will begin no later than mid-
February, and be gradual, with activity increasing over the first 5 
days. Ice camp deployment will be completed by March 15, before the 
pupping season. Displacement of seal lair construction or relocation to 
existing lairs outside of the ice camp area is unlikely, given the low 
average density of lairs (the average ringed seal lair density in the 
vicinity of Prudhoe Bay, Alaska is 1.58 lairs per km\2\ (Table 4) the 
relative footprint of the Navy's planned ice camp (2 km\2\; 0.77 
mi\2\), the lack of previous ringed seal observations on the ice during 
ICEX activities, and mitigation requirements that require the Navy to 
construct the ice camp and runway on first-year or multi-year ice 
without pressure ridges and require personnel to avoid areas of deep 
snow drift or pressure ridges.
    Given that mitigation measures require that the ice camp and runway 
be established on first-year or multi-year ice without pressure ridges, 
where ringed seals tend to build their lairs, it is extremely unlikely 
that a ringed seal would build a lair in the vicinity of the ice camp. 
This measure, together with the other mitigation measures required for 
operation of the ice camp, are expected to avoid impacts to the 
construction and use of ringed seal subnivean lairs, particularly given 
the already low average density of lairs, as described above. Given 
that ringed seal lairs are not expected to occur in the ice camp study 
area, NMFS would not expect ringed seals to relocate pups due to human 
disturbance from ice camp activities.
    Additional mitigation measures would also prevent damage to and 
disturbance of ringed seals and their lairs that could otherwise result 
from on-ice activities. Personnel on on-ice vehicles would observe for 
marine mammals, and would follow established routes when available, to 
avoid potential damage to or disturbance of lairs. Personnel on foot 
and operating on-ice vehicles would avoid deep snow drifts near 
pressure ridges, also to avoid potential damage to or disturbance of 
lairs. Further, personnel would maintain a 100 m (328 ft) distance from 
all observed marine mammals to avoid disturbing the animals due to the 
personnel's presence. Implementation of these measures would prevent 
ringed seal lairs from being crushed or damaged during ICEX24 
activities.
    In summary and as described above, the following factors primarily 
support our preliminary determination that the impacts resulting from 
this activity are not expected to adversely affect any of the species 
or stocks through effects on annual rates of recruitment or survival:
    <bullet> No Level A harassment (injury), serious injury, or 
mortality is anticipated or proposed for authorization;
    <bullet> Impacts would be limited to Level B harassment, primarily 
in the form of behavioral disturbance that results in minor changes in 
behavior;
    <bullet> TTS is expected to affect only a limited number of animals 
and is expected to be minor and short term;
    <bullet> The number of takes proposed to be authorized are low 
relative to the estimated abundances of the affected stock, even given 
the extent to which abundance is significantly underestimated;
    <bullet> Submarine training and testing activities would occur over 
only 4 weeks of the total 6-week activity period;
    <bullet> There would be no loss or modification of ringed seal 
habitat and minimal, temporary impacts on prey;
    <bullet> Physical impacts to ringed seal subnivean lairs would be 
avoided; and
    <bullet> Mitigation requirements for ice camp activities would 
prevent impacts to ringed seals during the pupping season.
    Based on the analysis contained herein of the likely effects of the 
specified activity on marine mammals and their habitat, and taking into 
consideration the implementation of the proposed monitoring and 
mitigation measures, NMFS preliminarily finds that the total marine 
mammal take from the proposed activity will have a negligible impact on 
all affected marine mammal species or stocks.

Unmitigable Adverse Impact Analysis and Determination

    In order to issue an IHA, NMFS must find that the specified 
activity will not have an ``unmitigable adverse impact'' on the 
subsistence uses of the affected marine mammal species or stocks by 
Alaskan Natives. NMFS has defined ``unmitigable adverse impact'' in 50 
CFR 216.103 as an impact resulting from the specified activity: (1) 
That is likely to reduce the availability of the species to a level 
insufficient for a harvest to meet subsistence needs by: (i) Causing 
the marine mammals to abandon or avoid hunting areas; (ii) Directly 
displacing subsistence users; or (iii) Placing physical barriers 
between the marine mammals and the subsistence hunters; and (2) That 
cannot be sufficiently mitigated by other measures to increase the 
availability of marine mammals to allow subsistence needs to be met.
    Impacts to marine mammals from the specified activity would mostly 
include limited, temporary behavioral disturbances of ringed seals; 
however, some TTS is also anticipated. No Level A harassment (injury), 
serious injury, or mortality of marine mammals is expected or proposed 
for authorization, and the activities are not expected to have any 
impacts on reproductive or survival rates of any marine mammal species.
    The specified activity and associated harassment of ringed seals 
would not be expected to impact marine mammals in numbers or locations 
sufficient to reduce their availability for subsistence harvest given 
the short-term, temporary nature of the activities, and the distance 
offshore from known subsistence hunting areas. The specified activity 
would occur for a brief period of time outside of the primary 
subsistence hunting season, and though seals are harvested for 
subsistence uses off the North Slope of Alaska, the ICEX24 Study Area 
is seaward of known subsistence hunting areas. (The Study Area boundary 
is approximately 50 km from shore at the closest point, though 
exercises will occur farther offshore.)
    The Navy proposes to provide advance public notice to local 
residents and other users of the Prudhoe Bay region of Navy activities 
and measures used to reduce impacts on resources. This includes 
notification to local Alaska Natives who hunt marine mammals for 
subsistence. If any Alaska Natives express concerns regarding project 
impacts to subsistence hunting of marine mammals, the Navy would

[[Page 85265]]

further communicate with the concerned individuals or community. The 
Navy would provide project information and clarification of the 
mitigation measures that will reduce impacts to marine mammals.
    Based on the description of the specified activity, the measures 
described to minimize adverse effects on the availability of marine 
mammals for subsistence purposes, and the proposed mitigation and 
monitoring measures, NMFS has preliminarily determined that there will 
not be an unmitigable adverse impact on subsistence uses from the 
Navy's proposed activities.

Endangered Species Act

    Section 7(a)(2) of the Endangered Species Act of 1973 (ESA; 16 
U.S.C. 1531 et seq.) requires that each Federal agency insure that any 
action it authorizes, funds, or carries out is not likely to jeopardize 
the continued existence of any endangered or threatened species or 
result in the destruction or adverse modification of designated 
critical habitat. To ensure ESA compliance for the issuance of IHAs, 
NMFS consults internally whenever we propose to authorize take for 
endangered or threatened species, in this case with NMFS' Alaska 
Regional Office (AKRO).
    NMFS OPR is proposing to authorize take of ringed seals, which are 
listed under the ESA. OPR has requested a section 7 consultation with 
the AKRO for the issuance of this IHA. The Navy has also requested a 
section 7 consultation with AKRO for ICEX Study Area activities. OPR 
will conclude the ESA consultation prior to reaching a determination 
regarding the proposed issuance of the authorization.

Proposed Authorization

    As a result of these preliminary determinations, NMFS proposes to 
issue an IHA to the Navy for conducting submarine training and testing 
activities in the Arctic Ocean beginning in February 2024, provided the 
previously mentioned mitigation, monitoring, and reporting requirements 
are incorporated. A draft of the proposed IHA can be found at: https://www.fisheries.noaa.gov/national/marine-mammal-protection/incidental-take-authorizations-military-readiness-activities.

Request for Public Comments

    We request comment on our analyses, the proposed authorization, and 
any other aspect of this notice of proposed IHA for the proposed ICEX24 
activities. We also request comment on the potential renewal of this 
proposed IHA as described in the paragraph below. Please include with 
your comments any supporting data or literature citations to help 
inform decisions on the request for this IHA or a subsequent renewal 
IHA.
    On a case-by-case basis, NMFS may issue a 1-time, 1-year renewal 
IHA following notice to the public providing an additional 15 days for 
public comments when (1) up to another year of identical or nearly 
identical activities as described in the Description of Proposed 
Activity section of this notice is planned or (2) the activities as 
described in the Description of Proposed Activity section of this 
notice would not be completed by the time the IHA expires and a renewal 
would allow for completion of the activities beyond that described in 
the Dates and Duration section of this notice, provided all of the 
following conditions are met:
    <bullet> A request for renewal is received no later than 60 days 
prior to the needed renewal IHA effective date (recognizing that the 
renewal IHA expiration date cannot extend beyond 1 year from expiration 
of the initial IHA); and
    <bullet> The request for renewal must include the following:
    (1) An explanation that the activities to be conducted under the 
requested renewal IHA are identical to the activities analyzed under 
the initial IHA, are a subset of the activities, or include changes so 
minor (e.g., reduction in pile size) that the changes do not affect the 
previous analyses, mitigation and monitoring requirements, or take 
estimates (with the exception of reducing the type or amount of take); 
and
    (2) A preliminary monitoring report showing the results of the 
required monitoring to date and an explanation showing that the 
monitoring results do not indicate impacts of a scale or nature not 
previously analyzed or authorized.
    <bullet> Upon review of the request for renewal, the status of the 
affected species or stocks, and any other pertinent information, NMFS 
determines that there are no more than minor changes in the activities, 
the proposed renewal timeframe does not significantly alter the 
agency's initial impact findings, the mitigation and monitoring 
measures will remain the same and appropriate, and the findings in the 
initial IHA remain valid.

    Dated: December 4, 2023.
Catherine Marzin,
Acting Director, Office of Protected Resources, National Marine 
Fisheries Service.
[FR Doc. 2023-26913 Filed 12-6-23; 8:45 am]
BILLING CODE 3510-22-P


</pre><script data-cfasync="false" src="/cdn-cgi/scripts/5c5dd728/cloudflare-static/email-decode.min.js"></script></body>
</html>